Donald Trump’s social media post that showed a purported endorsement for the presidency from the JP Morgan chief executive, Jamie Dimon, among the most influential investment bankers on Wall Street, is false, a representative confirmed on Friday.

The Truth Social post – what appears to be a screenshot of a tweet with a siren emoji and text claiming Dimon had endorsed Trump, with a photo of Dimon – appeared at 1.56pm ET on Friday, as Trump was flying to Augusta, Georgia, for a campaign event.

But Dimon has not endorsed Trump or made any endorsements in the 2024 presidential race, according to a JPMorgan Chase spokesperson. And Dimon has not contributed any money to the Trump campaign or to Trump’s Democratic rival, Kamala Harris.

The instant denial from the bank has not led Trump to take down the post, which has more than 3,500 reposts and more than 11,000 likes, even as he distanced himself from the claim when he was confronted about it after he landed in Augusta.

“I don’t know anything about it,” Trump said. When a reporter noted he had posted it on his social media platform, Trump suggested one of his aides had posted the claim.

When the reporter pressed him to comment, Trump replied: “I don’t know – was it him or no?” And when a reporter told him a spokesperson for the bank had confirmed it was false, Trump evaded responsibility: “Well, then, somebody is using his name.”

The post was the latest in a series of false claims Trump has advanced in recent weeks, which have become increasingly brazen with fewer than four weeks until the November election and have occurred at a higher clip.

At least part of the reason for the uptick in falsehoods is Trump’s obsession with news and posts about himself, and his impulse to repost anything politically positive for him without regard as to its veracity.

But the fake Dimon claim stands apart because of his significance to Trump, who has long admired Dimon’s success and would covet the peer recognition at a time when he has struggled with celebrity endorsements compared with Harris, who has received backing from the likes of Taylor Swift.

The Trump campaign had hoped that Dimon might speak at the Republican national convention in July, according to people familiar with the matter, but he did not end up accepting the invitation.

Dimon is particularly noteworthy in corporate finance for his tenure at JP Morgan, which became the largest bank in the United States after he led the acquisition of the troubled banks Bear Stearns and Washington Mutual during the 2008 financial crisis.

As a result, Trump was pleased when Dimon offered some compliments about the Trump administration’s economic policies during an interview with CNBC at the World Economic Summit in Davos, Switzerland.

“Take a step back, be honest. He was kind of right about Nato, kind of right on immigration,” Dimon said in January. “He grew the economy quite well. Trade tax reform worked. He was right about some of China.”

Trump and his allies widely shared Dimon’s comments. This year, Trump suggested he would consider appointing Dimon his treasury secretary if he won the election, but later retracted the offer.

Pete Buttigieg, the transportation secretary, shot down criticism by Elon Musk on the government’s handling of Hurricane Helene relief efforts, accusing the SpaceX CEO of spreading misinformation.

Musk accused the Federal Emergency Management Agency (Fema) of blocking his satellite internet company, Starlink, from delivering to parts of North Carolina decimated by the hurricane, a claim both Fema and Buttigieg said was false.

“No one is shutting down the airspace and FAA doesn’t block legitimate rescue and recovery flights. If you’re encountering a problem give me a call,” Buttigieg wrote. Musk replied that he had seen hundreds of such reports and would phone.

Musk had spent several hours on Friday raging on X against Fema over what he called “belligerent government incompetence”. Posting texts allegedly received from “a SpaceX engineer on the ground”, he accused the federal agency of blockading the disaster area and preventing private helicopters from delivering Starlink terminals, which connect to satellite internet service, and other supplies.

Musk wrote, “SpaceX engineers are trying to deliver Starlink terminals & supplies to devastated areas in North Carolina right now and @FEMA is both failing to help AND won’t let others help. This is unconscionable!!”

When reached for comment on Musk’s allegations, Fema issued a statement similar to Buttigieg’s: “The claims about FEMA confiscating or taking commodities, supplies or resources in North Carolina, Tennessee, or any state impacted by Helene are false.

“FEMA has helped provide Starlink terminals to the state of North Carolina, including to the Eastern Band of Cherokee Nation and critical lifeline locations as determined by the state. These units are supporting state and local municipalities, Urban Search and Rescue and disaster coordination. Starlink units have been sent to multiple states in support of Hurricane Helene response efforts,” said Jaclyn Rothenberg, Fema director of public affairs.

Still, Donald Trump amplified Musk’s claims on his app Truth Social. Musk said he would join the former president at a rally in Pennsylvania on Saturday.

False information has swirled in the communications blackout that has followed Hurricane Helene’s devastation. Phone and power lines were down across the south. Trump falsely accused Joe Biden of failing to call Georgia’s governor after the storm, when Biden had phoned Brian Kemp.

Musk has a history of inserting himself into rescue operations. In 2018, he offered to deliver a small submersible to Thailand to assist with the rescue of a boys’ soccer team, which divers on the scene called a “PR stunt”. In response, Musk called the head rescuer a “pedo guy”, eliciting a defamation suit that Musk later won.

Joe Biden had terse words at the White House on Friday for Benjamin Netanyahu, saying he didn’t know whether the Israeli prime minister was holding up a peace deal in the Middle East – where Israel is at war with Hamas in Gaza and on a military offensive against Hezbollah in Lebanon – in order to influence the outcome of the 2024 US presidential election.

“No administration has helped Israel more than I have. None. None, none. And I think Bibi should remember that,” Biden said, using Netanyahu’s nickname. He added: “And whether he’s trying to influence the election, I don’t know – but I’m not counting on that.”

The US president made a surprise and rare appearance in the west wing briefing room and answered reporters’ questions there for the first time in his presidency.

He was responding to comments made by one of his allies, Chris Murphy, a Democratic US senator of Connecticut, who said on CNN this week that he was concerned Netanyahu had little interest in a peace deal in part because of American politics.

The two leaders have long managed a complicated relationship, but they are running out of space to maneuver as their views on the Israel-Gaza war diverge and their political futures hang in the balance.

Biden has pushed for months for a ceasefire agreement in Gaza – and the president and his aides boosted the idea repeatedly that they were close to success – but a ceasefire has not materialized. Antony Blinken, the secretary of state, has engaged in shuttle diplomacy to Israel and to peace talks via intermediaries, but to no avail and, in some cases, Netanyahu has publicly resisted the prospect while US and Israeli officials continue to talk in private about eking out a deal.

Meanwhile, Israel has recently pressed forward on two fronts, pursuing a ground incursion into Lebanon against Hezbollah and conducting strikes in Gaza. And it has vowed to retaliate for Iran’s ballistic missile attack this week, as the region braced for further escalation.

Biden said there had been no decision yet on what type of response there would be toward Iran, though there has been talk about Israel striking Iran’s oilfields: “I think if I were in their shoes, I’d be thinking about other alternatives than striking oilfields.”

Biden pushed back against the idea that he was seeking a meeting with Netanyahu to discuss the response to Iran. He wasn’t, he said.

“I’m assuming when they make a decision on how they’re going to respond, we will then have a discussion,” he said.

Netanyahu has grown increasingly resistant to Biden’s efforts. Biden has in turn publicly held up delivery of heavy bombs to Israel and increasingly voiced concerns over an all-out war in the Middle East and yet has never acquiesced to political calls at home or internationally for a halt on US arms sales to Israel.

“I don’t believe there’s going to be an all-out war,” Biden said on Thursday evening. “I think we can avoid it. But there’s a lot to do yet.”

Biden has remained consistent in his support for Israel in the aftermath of the 7 October Hamas attacks in Israel. Since then, with few exceptions, Biden has supported ongoing and enhanced US arms transfers to Israel while merely cautioning the Israelis to be careful to avoid civilian casualties.

Biden has also ordered the US military to step up its profile in the region to protect Israel from attacks by Hamas, Hezbollah, the Iranian-backed Houthi rebels in Yemen and Iran itself. In April, and again earlier this week, the US was a leading player in shooting down missiles fired by Iran into Israel.

On Thursday, Biden said the US was “discussing” with Israel the possibility of Israeli strikes on Iran’s oil infrastructure.

His off-the-cuff remark, which immediately sent oil prices soaring, did not make clear whether his administration was holding internal discussions or talking directly to Israel, nor did he clarify what his attitude was to such an attack.

Asked to clarify those comments, Biden told reporters on Friday: “Look, the Israelis have not concluded what they’re going to do in terms of a strike. That’s under discussion.”

Kamala Harris also has not taken a different stance on arms sales but has spoken more assertively for months to demand an immediate ceasefire in Gaza and has decried civilian killings in Israel’s war in the Palestinian territory.

The Associated Press contributed reporting

Sky News has pulled out of an interview with Boris Johnson after its political editor was told she could not make an audio recording or transcript of the talk.

The former prime minister had promised to “reveal what really happened during my time as [London] mayor, foreign secretary and PM” during the conversation next week as he promotes his memoir Unleashed. Johnson’s interview with the BBC was dropped earlier this week after the presenter Laura Kuenssberg mistakenly sent him her briefing notes.

In a post on X on Friday, Beth Rigby said: “I was looking forward to interviewing Boris Johnson at Cheltenham but regrettably I can’t go ahead with the event because I am not allowed [to] make an audio recording or transcript of the interview.

“As a journalist in conversation with a former PM at a public event, I can only proceed if we do it on the record. I’m sorry to have to pull out.”

On Wednesday, Kuenssberg said she had sent Johnson the notes for her interview “in a message meant for my team”, and cancelled the discussion with the former Conservative party leader.

The BBC’s former political editor said the error was “embarrassing and disappointing”, and meant it was “not right for the interview to go ahead”.

In an interview with ITV News broadcast on Friday night, Johnson said he regretted apologising over his government’s lockdown parties in Downing Street in 2020. In his memoir, he wrote that he made a “mistake” issuing “pathetic” and “grovelling” apologies over partygate, which he said “made it look as though we were far more culpable than we were”.

Tom Bradby, who presents ITV News at Ten, asked Johnson: “You basically say: ‘It wasn’t a big deal. I regret apologising.’ Is that really your position? Did you regret apologising to the queen?”

Johnson refused to answer and replied: “I don’t discuss my conversations with the queen.”

He added: “What I was trying to say there was, I think that the blanket apology – the sort of apology I issued right at the beginning – I think the trouble with it was that afterwards, all the accusations that then rained down on officials who’d been working very hard in No 10 and elsewhere were thought to be true.

“And by apologising I had sort of inadvertently validated the entire corpus and it wasn’t fair on those people.”

The memoir also claimed that Gavin Williamson blocked a £400m deal to bring the British-Iranian prisoner Nazanin Zaghari-Ratcliffe home from Iran five years before she was released, on the basis the money could be used by Hezbollah.

Johnson said that in 2017 he reached an agreement for the dual national’s release in return for money owed by Britain to Tehran since the 1970s. The Treasury and the Foreign Office approved, but No 10 insisted the decision needed to be signed off by all relevant departments, including the Ministry of Defence, which at the time was headed by Williamson.

The chief operating officer of Truth Social’s parent company has resigned, and the company must hand over almost 800,000 shares to one of its investors as part of a court ruling, according to a regulatory filing.

Andrew Northwall, the former COO, resigned from Trump Media & Technology Group Corp late last month, according to the Securities and Exchange Commission filing, adding that the company plans to “transition his duties internally”.

No further details were provided about the resignation. He joined the company in December 2021, according to his LinkedIn page.

The SEC filing also disclosed that a Delaware court ruled last month that 785,825 shares of Trump Media must be released to Arc Global Investments II. Both parties have been feuding over how many shares Arc was owed after Trump Media combined with Digital World Acquisition Corp. The court said that ARC and Trump Media have the option to file an appeal within 30 days after its final order.

Trump Media runs the social media platform Truth Social, which Trump created after he was banned from Twitter and Facebook following the Capitol riot on 6 January 2021. Based in Sarasota, Florida, the company has been losing money and struggling to raise revenue. It lost nearly $58.2m last year while generating only $4.1m in revenue, according to regulatory filings.

Shares of Trump Media have been considered a meme stock by some market experts, which is a nickname given to stocks that get caught up in buzz online and shoot way beyond what traditional analysis says they are worth. The stock has fluctuated for several months, with trading largely driven by individual investors who are typically considered less sophisticated than day traders.

Late last month Trump Media’s stock fell to its lowest level ever on the first trading day that its biggest shareholder, Donald Trump, was free to sell his stake in the company behind the Truth Social platform.

Trump Media, whose shares are commonly called TMTG, started trading publicly in March. When the company made its debut on the Nasdaq in March, the shares hit a high of $79.38.

Shares of Trump Media & Technology rose slightly to $16.20 before the market open on Friday.

When Andrew Carter and Adam DeMartino started their business Smallhold in 2017, they set out with a simple vision they thought could have a big impact: feed people mushrooms.

“Mushrooms are one of the most sustainable calories on the planet, in every aspect,” Carter said, whether you’re looking at water, waste, plastic use or greenhouse gas emissions. “We just wanted to get more people eating them.”

For the better part of seven years, Smallhold successfully did just that, getting specialty mushrooms such as shiitake, blue oyster and trumpets into grocery stores and on to Americans’ plates. And they built a cult favorite brand while doing so – a feat made notable by how much harder it is to accomplish with produce than, say, processed snack foods. (Think about how differently you shop for chips or ice-cream, on the lookout for a specific brand you like, versus peaches or tomatoes, the brand of which you may not even notice.)

As mushrooms became emblematic of a new vision of sustainability at the start of the pandemic lockdowns, achieving zeitgeist-y star status, Smallhold found itself both riding that wave and helping propel it, earning a range of buzzy media coverage and being valued at $90m at its peak. Just six years after starting in a shipping container in Brooklyn, the brand had built out farms in New York, Texas and California, and had begun selling in 1,400 stores across the country, including Whole Foods.

“We gave others hope that a sustainable business could rise quickly, become popular, and change an entire category for the better,” said DeMartino. Smallhold was just one of a host of food startups that have cropped up with the promise that they’re growing food more sustainably or reducing waste.

So it came as a disappointing shock to many when the founders both stepped down this spring and Smallhold announced that it was filing for bankruptcy shortly thereafter.

Though the company was taken over by investors who restructured and brought the company out of bankruptcy at the end of August, Smallhold emerged as a “shadow” of the company DeMartino once envisioned; it shut down its farms and laid off much of its staff without severance, to the dismay of the founders and customers who had come to associate the brand with the ethical treatment of its employees and farmers as well as the earth. (The brand’s current leadership declined to comment for this article.)

What does the brand’s trajectory mean for the prospects of using entrepreneurship to right traditional agriculture’s wrongs? In the example of Smallhold and other produce-focused startups like it, there are lessons to be learned about what role business can – and can’t – play in fixing our food system.

Do: find a niche, and sell more than sustainability

Elly Truesdell was working at Whole Foods as a “forager” who helped the grocery chain identify new local suppliers when Smallhold started out, and she remembers being impressed at their unique offering. Where most shoppers had only encountered the most common varieties of button mushrooms, Smallhold was introducing varieties with more interesting and varied flavor profiles, such as lion’s mane and blue oyster.

“I traveled the country and visited a ton of local food stores and other grocers and very, very rarely could you see specialty mushrooms of the varieties that they were growing in grocery stores,” she said. That’s some of what convinced her, once she left Whole Foods to get into venture capital with a focus on food businesses, to invest in Smallhold.

For a world increasingly thinking about both personal and planetary health, mushrooms hold great appeal as an easy and nutritious meat alternative. And Smallhold was paying farmers a living wage to grow them on waste material, using minimal water and electricity, composting the leftover materials after, and selling their product in compostable retail packaging (an industry first).

But startups that gain a foothold in the produce aisle have to offer customers more than that to succeed, Truesdell said. “You cannot hang your hat on sustainability only. Product quality, cost – all of the things that matter in a typical food business still matter.”

In some ways, Smallhold excelled at that: in addition to the unique flavor and high quality of its produce, it also built a strong brand through a combination of the charming aesthetics of the mushrooms themselves, a witty social media presence and the relationships its founders built with tastemakers who helped cement Smallhold as part of the zeitgeist.

Smallhold isn’t the only produce company that has benefited from creating a unique visual identity. Bowery Farming, an indoor agriculture company that sells greens and berries, and Gotham Greens, which sells salad greens, dressings and herbs, are two others that have invested in top-notch design and branding.

While all three companies have claimed to be growing food more sustainably than peer companies in their categories, their unique approach to branding produce is part of what lures in new customers, Truesdell noted.

Don’t: take on too much money

Entrepreneurs who want their business to be sustainable by environmental standards have to also be sustainable in the financial sense of the word.

Though what Smallhold set out to do was sell mushrooms that would help people “reconnect with their food, environment, and farmers”, the technology it was using to do so was often what excited funders. “Over time, we were really leading with that,” said DeMartino. “The pitch got crafted around technology further and further.” He often felt that they were adding tech that was cool, but overcomplicated things: “You don’t need to press a button to open a window. You can just open the window,” he said.

Plus, creating and maintaining the technology infrastructure was expensive, which made building new farms costly. That in turn made becoming profitable more difficult to do – and when venture capitalists are looking for a return on their investment quickly, a slow path to profitability can be a death knell.

“VCs need their money back,” said Ari Greensburg, professor of entrepreneurship and management at NYU Stern. “They need you to get there by five, six years, seven maximum … If you can’t do that, they abandon you.”

That is, in some sense, what happened to Smallhold: after years of ample VC funding, investors decided they weren’t making enough progress toward profitability, stopped cutting them checks, and the company was left without adequate cashflow.

Smallhold wasn’t the only buzzy produce company to go bankrupt under these circumstances. AeroFarms and AppHarvest, two other indoor farming companies that had attracted big venture capital investments in the past, also declared bankruptcy last year when the VC landscape began to shift away from its former optimism about tech-based food startups.

Lessons for other entrepreneurs

It’s easy to tell an entrepreneur that it’s dangerous to take on VC funding, but often harder to offer viable alternatives for startups that need cash. But those options do exist, insisted Truesdell, especially for agriculture companies. She pointed to Ark Foods, a produce startup founded in 2013 that helped create the US market for shishito peppers, as an example. Though the company has taken on some modest equity investments from funds including Truesdell’s, those haven’t made up the bulk of the company’s funding.

“They rely a ton on farm credit and on loans from the Farm Bureau, rather than on venture dollars,” she said. “They’re almost always hovering at break-even or slightly profitable, so that they’re not in this difficult situation that companies like Smallhold found themselves in.” She named the family-owned salad and greens business Taylor Farms, which has opted to grow slowly over time rather than taking on big investments in the hopes of scaling up quickly, as another example of how to do things differently.

There’s no one-size-fits-all way to build or run a produce startup to ensure that it’ll be around in the long run, and the most effective strategy for changing the food system for the better won’t rely on entrepreneurship alone, but will incorporate policy change and regulation, too.

But there are a few lessons worth trying to take away from the successes and failures of the startups that have tried to do so in the last few years: build a strong brand, even in a category like produce that hasn’t historically been known for branding. Offer sustainability, but pair that with other values, such as new flavors or higher quality to lure in customers. And take financial responsibility just as seriously as planetary and social responsibility.

“No matter how much you love it, this business runs on money, not on love,” DeMartino said. “We needed to make really key decisions around that in order to sustain the vision of a circular economy business.”

Lastly, learn to define success on your own terms.

Despite its eventual bankruptcy, Smallhold did help carve out a market across the nation for specialty mushrooms – and getting more people hooked on what could be the “most sustainable calories on the planet” is a legacy the company’s founders think is worth celebrating.

For decades, drinking water fluoridation opponents were often portrayed as a fringe element and conspiracy theorists, but a federal ruling in the US may put an end to the practice and marks a pivotal point in their campaign to convince the public and policymakers of the substance’s dangers for infants’ developing brains.

Armed with a growing body of scientific evidence pointing toward fluoride’s neurotoxicity, public health advocates say the legal win shows they are overcoming “institutional inertia” and the unwillingness of federal public health agencies to admit they may have been wrong.

The order last week requiring the US Environmental Protection Agency (EPA) to begin the process of strengthening fluoride regulations represents a “landmark” legal win that has long been in the making, said Stuart Cooper, director of the Fluoridation Action Network advocacy group.

“After many years of them ignoring us and defending fluoridation, we had an opportunity to get a fair and balanced adjudication in courts,” Cooper said.

The Obama-appointed US judge Edward Chen found fluoridation could cause developmental damage and lower IQ in children at levels to which the public is generally exposed in drinking water. Though the ruling did not state the level at which fluoridation would damage brains, the levels in US water present an unreasonable risk, the court found.

The EPA now must perform a risk assessment that is among the first steps in setting new limits under the Toxic Substances Control Act.

US water has been fluoridated since 1945, though the recommended levels have since been lowered over health risks. Fluoride strengthens teeth and reduces cavities by replacing minerals lost during normal wear and tear, according to the US Centers for Disease Control and Prevention, and dentistry groups say it protects young children’s gums and developing teeth.

It is added to drinking water for more than 200 million Americans, or about 75% of the population, at recommended levels of 0.7 milligrams of fluoride per liter of water.

Though those opposed to fluoridation can point to credible evidence to back their case, anti-fluoridation history has included conspiracy theories that the process was a post-second world war communist plot, or, later, a coordinated effort to sap US society of intelligence.

But there has always been evidence of the risks, and the practice is rare in most other countries, including those in Europe. The last 15 years have seen an “uptick” in high-quality scientific research demonstrated the risks, said Michael Connett, a Food and Water Watch lead attorney on the case.

The EPA had been “a good soldier” and toed the federal government’s line, but that required it to ignore evidence and abandon its statutorily required duties, Connett said.

“You have agencies that have aggressively promoted fluoridation for decades in a very un-nuanced, sledgehammer way, so it’s quite a departure from that party line to say, ‘Oh, oops, looks it might actually be damaging the brain,” Connett said. “There’s an institutional credibility and inertia issue.”

Still, even after the ruling, many fluoridation supporters are not backing down. Much of the medical establishment supports the process. In a statement last week, the American Dental Association, which supports fluoridation, said: “The key takeaway for the public and public health community from this ruling is that it does not conclude with any certainty that fluoridated water is injurious to public health.’”

Cooper pointed to a statement made by an American Pediatric Association official during the court case in which she said she would not oppose fluoridation even if it reduced five IQ points for up to 10% of the population.

Cooper said the fight over fluoridation over the last several decades had been with the medical establishment and regulatory agencies, while everyday residents generally agreed that the practice should end.

“The vast majority of the public was always on our side, there was never a citizen who said, ‘Yes, please give us fluoridated water,’” Cooper said.

The shift in part picked up momentum as scientists like Linda Birnbaum, a former head of the EPA’s toxic chemicals program, came out in support of ending fluoridation, and some government agencies over the last several years found unreasonable risk.

“When do we know enough to revise long-held beliefs? We are reminded of the discovery of neurotoxic effects of lead that led to the successful banning of lead in gasoline and paint,” Birnbaum said in a 2020 op-ed.

In the ruling’s wake, four water systems, including that which provides water to Salt Lake City, have stopped or suspended fluoridation.

Despite the win, Connett said he did not expect support for fluoridation to immediately vanish.

“There’s a scientific paradigm and deep beliefs that exist that say fluoridation is safe and effective, and that doesn’t just go away overnight,” he added.

Donald Trump unleashed a foul-mouthed tirade about undocumented immigrants and predicted that this “could be the last election we ever have” if Kamala Harris wins during a private fundraising dinner this summer.

The Guardian obtained a 12-minute recording of a speech that the Republican presidential nominee gave at a dinner on 10 August in Aspen, Colorado, where attendees were required to donate anywhere from $25,000 to $500,000 a couple.

Trump devoted most of his address to border security and immigration, recycling xenophobic claims now familiar from his rallies. “Radical leftwing lunatics” want people to come in from prisons, mental institutions and insane asylums, he asserted without evidence, adding that the US was harbouring “a record number of terrorists”.

The former president insisted that “smart, very streetwise” leaders of Venezuela and other South American countries were sending murderers and drug dealers to the US to reduce their own crime rates, relieve the burden on their prisons and save money.

Trump cited a false example of 22 people he claimed had come to the US after being released from prison in the Democratic Republic of the Congo. “We said, ‘Where do you come from?’ They said, ‘Prison’. ‘What did you do?’ ‘None of your fucking business what we did.’ You know why? Because they’re murderers.”

The candidate added, “I hate to use that foul language”, apparently recognising that his use of the F-word went further than his campaign rallies. The Congolese government has said there is no truth to Trump’s statements.

The candidate went on: “These are the toughest people. These people are coming in from Africa, from the Middle East. They’re coming in from all parts of Asia, the bad parts, the parts where they’re rough, and the only thing good is they make our criminals look extremely nice. They make our Hell’s Angels look like the nicest people on earth.”

Studies show that immigrants are less likely to commit crime than native-born Americans.

Trump flew to Aspen on a Gulfstream G-550 jet once owned by Jeffrey Epstein, the late disgraced financier and convicted sex offender, after his own private plane – a Boeing 757 known colloquially as Trump Force One – encountered engine trouble.

The dinner was held at the $38m home of the investors and art collectors John and Amy Phelan. Guests included the casino mogul Steve Wynn, billionaire businessman Thomas Peterffy, Texas governor Greg Abbott, Florida congressman Byron Donalds, Colorado congresswoman Lauren Boebert and former Colorado senator Cory Gardner.

Trump, who instigated an attempted coup on 6 January 2021 and has claimed that his Democratic rival Harris poses the true threat to democracy, used the exclusive event to warn of dire consequences if she becomes president.

“Look, we gotta win and if we don’t win this country’s going to hell,” he said. “You know, there’s an expression, this could be the last election we ever have and it’s an expression that I really believe, and I believe that this could be the last election we ever have.”

The ex-president was speaking a month before his first and probably only televised debate against Harris, of which opinion polls and pundits would widely judge her to be the clear winner. That was not what he predicted.

“I’m telling you we have a radical left person that’s going be president – if she wins it’s going to be a disaster – she wants to be president very badly. Thank God she’s supposed to be horrible at debating, although she’s nasty, and she’s supposed to be really bad at interviews. She can’t do an interview.”

Trump also claimed that Harris supports the “defund the police” movement, suggesting that she was a typical politician who will revert to type once she is elected.

“Her policy is defund the police. She wants to defund the police. She wants open borders. With a politician – and I’ve seen it because I’ve been on both sides of politics for a long time; now, a short time for this side but I was always a contributor – she wants to go out and she wants to defund the police. And they always go back to their original plot. They always do.”

Harris, a former courtroom prosecutor, did voice support for the “defund the police” movement in a radio interview in June 2020 but later reversed her position after becoming Joe Biden’s running mate.

Trump also reflected on surviving an assassination attempt at a July rally in Butler, Pennsylvania, where 20-year-old Thomas Crooks opened fire from a rooftop, killing firefighter Corey Comperatore, 50, and injuring two other Trump supporters.

Trump told how members of his Florida golf club, Mar-a-Lago, asked to make a contribution to Comperatore’s family. “I said absolutely and they gave me a cheque for a million dollars. That’s a lot of money. Maybe even more impressively we put out a GoFundMe and we raised more than $6m for the group that got hurt, which is essentially three people.”

Then, recalling a meeting with Comperatore’s widow, Helen, he made a risky attempt to find humour in the tragedy. “So they’re going to get millions of dollars but the woman, the wife, this beautiful woman, I handed her the cheque – we handed her the cheque – and she said, ‘This is so nice, and I appreciate it, but I’d much rather have my husband.’ Now, I know some of the women in this room wouldn’t say the same.”

As dinner guests erupted in laughter, Trump quipped: “I know at least four couples. There are four couples, Governor [Abbott], that I know and you’re not one of them. At least four couples here would have been thrilled, actually.”

The event is understood to have raised $12m for Trump’s campaign but was not enough to prevent Harris raising more than four times as much as her opponent in August, the first full month of her bid for the White House.

Political leaders “walking the talk” on climate action by flying less or eating less meat could be a “crucial missing link” in fighting global heating, according to a study.

Researchers found that people are significantly more willing to reduce their own carbon footprint if they see leaders doing the same. The finding, by psychologists in the UK, was not a given, as green action by high-profile people can sometimes be dismissed as virtue-signalling.

The study also found that people were significantly less willing to change their behaviour when leaders do not lead by example. The former prime minister Rishi Sunak took 40 helicopter and small jet flights within the UK while in office, according to a freedom of information request by the Guardian.

The findings are significant because many experts argue that encouraging and enabling behaviour change by people is vital to tackling global heating. But there have been strikingly few examples of politicians leading by example.

Research for the UK Climate Change Committee estimates that 60% of the emissions cuts still required will involve behaviour change, and the Intergovernmental Panel on Climate Change increasingly recognises this need. To date, politicians have focused only on the systemic changes also needed, such as renewable energy rollouts and international agreements.

A second study suggests why politicians are reluctant to publicise their personal green actions. Even MPs who strongly back climate action are afraid of criticism, such as being labelled fanatics or hypocrites if other aspects of their lives remain high-carbon.

There is the possibility of a win-win situation, the first study suggests, as it shows that people’s overall approval of political leaders increases for those leading by example. The key, the researchers say, is for leaders to be consistent over time – avoiding green stunts – and to acknowledge that some changes may be too difficult or costly for everyone to make, such as using public transport, buying an electric car or installing a heat pump.

“[Leading by example] is a missing link because climate change is addressed politically in a technocratic, top-down way: new technology, changed systems of energy provision,” said Dr Steve Westlake, from Cardiff University, who led both studies. “These solutions avoid impact on people’s daily lives.”

“From now on, progress is really going to require people to change their behaviour and yet that has been avoided by politicians. We don’t like being told what to do,” he said. “But taking personal action can bridge that gap between the individual and the system. If we see leaders saying ‘here’s what I am doing’, it brings it back to daily life.” Westlake said there existed a stand-off, with politicians reluctant to ask people to change their behaviour and people reluctant to change without politicians showing the way.

Politicians failing to lead by example can also lead to people feeling that global heating was not a crisis, he said, despite the clear scientific evidence. “The urgency of their words [on climate] doesn’t seem to be matched by the signals they send through their behaviour. I think many leaders are still sending the signal that no emergency response is required.”

The study on leading by example, published in the journal Humanities and Social Sciences Communications, told almost 1,300 people about a political leader who was backing technological and international climate action and saying behaviour change was necessary, too. In some groups, the leader said they had made those changes themselves while in others the leader said they had not yet done so. The leaders did not directly call on people to make the behaviour changes.

“We found that leading by example sends very strong signals,” Westlake said. “We found an increase in people’s willingness to adopt low-carbon behaviour if they see leaders doing it, and the reverse. There’s also a really strong reaction in terms of perceptions of the leader.” Those leading by example were seen as more competent, effective and caring.

The study also told some groups about celebrities, rather than political leaders, and found the same strong effect of leading by example.

Instances of high-profile politicians leading by example are yet to occur, Westlake said, unlike negative examples. “What springs to mind is Boris Johnson flying back from the Cop26 climate conference” in Glasgow in 2021 rather than taking a train. “That is a quite powerful message,” he said.

The second study, published in the journal Energy Research & Social Science, was based on interviews with 19 MPs. It found those who were taking personal green action “tended to do this quietly for fear of negative reactions from the media, political rivals, and constituents”. The former prime minister David Cameron’s journey from “hugging a husky” in the Arctic to “cutting the green crap” was frequently cited by the MPs as showing the risk of being inconsistent.

Dr Maya Singer Hobb, from the Institute for Public Policy Research thinktank, said: “This research confirms what we hear again and again in our engagement with the public, which is that people are sensitive to hypocrisy; ‘why should I change my behaviour when politicians are taking private jets?’”

“There is a strong imperative for politicians to lead by example, both as a means of shifting the norms around behaviour change, but also from a fairness angle, since it is likely they will have greater emissions than most people,” she said.

“The research also suggests that fears of appearing ‘too virtuous’ are perhaps overblown, again reassuring politicians that they can take personal action. The democratic mandate for climate action is high, and the politicians will better maintain public support for green policies if they show that the responsibility for action will be fairly shared.”