US President Joe Biden suffered a stunning blow Wednesday when actor and leading Democratic supporter George Clooney urged him to drop his reelection bid, while party heavyweight Nancy Pelosi declined to back his candidacy.

As the 81-year-old tried to show his leadership credentials at a NATO summit in Washington, domestic pressure mounted on Biden to quit following his disastrous debate performance against Donald Trump.

Biden has been trying to stem a growing tide of Democrats saying that he cannot win in November, but Clooney’s surprise intervention squashed his efforts to turn the page on the crisis.

The Hollywood star penned a devastating editorial in the New York Times just three weeks after hosting a huge fundraiser in Los Angeles that raised nearly $30 million for Biden.

“It’s devastating to say it, but the Joe Biden I was with three weeks ago at the fundraiser was not the Joe ‘big F-ing deal’ Biden of 2010,” wrote Clooney.

“He wasn’t even the Joe Biden of 2020. He was the same man we all witnessed at the debate.”

Clooney said that Biden would lose the presidential election, and Democrats would also lose in the Senate and House of Representatives.

At the fundraiser in Los Angeles co-hosted by Clooney and fellow movie star Julia Roberts, Biden appeared tired as he took to the stage alongside former president Barack Obama.

He had flown straight to California from the G7 summit in Italy and has since blamed jetlag, and a cold, for his disastrous performance in a June 27 television debate with Donald Trump.

Fellow actor Michael Douglas followed up Wednesday, saying he was “deeply, deeply” concerned about Biden’s prospects.

In response to Clooney’s editorial, the Biden campaign pointed to the president’s statements on Monday saying he was “committed” to running again in November.

Overwhelmingly negative

While top Democrats broadly but unenthusiastically backed him on Tuesday, Biden’s efforts to stop the bleeding increasingly looked to be in vain.

Former House speaker Pelosi, 86, said time was running out for Biden to decide whether to end his candidacy, ignoring Biden’s repeated insistence that he is committed to run.

“It’s up to the president to decide if he is going to run,” she told MSNBC.

“We’re all encouraging him to make that decision because the time is running short.”

Pelosi said Biden should however delay any final decision until after NATO’s 75th anniversary summit in Washington, which ends on Thursday with what will be a closely watched press conference by the president.

Fellow NATO leaders appeared to rally round Biden as he greeted them on arrival.

French President Emmanuel Macron, himself under pressure after calling an inconclusive snap election, gave the older man a hug and a firm handshake on the podium.

Biden, who gave a forceful speech pledging new air defenses for Ukraine as the summit opened on Tuesday, got through his opening remarks with only a couple of verbal stumbles.

But his every move from now until November will now be watched for evidence of age-related frailty or ill health.

He also dropped in on union leaders on Wednesday in another bid to shore up his key supporters.

At least eight House Democrats have openly called on Biden to not seek reelection, with New York Congressman Pat Ryan jumping ship on Tuesday.

Colorado’s Michael Bennet became the first Senate Democrat to publicly turn on the president, saying Biden would lose if he stayed on the ballot.

“Donald Trump is on track, I think, to win this election, and maybe win it by a landslide and take with it the Senate and the House,” Bennet told CNN.

Former White House communications director Kate Bedingfield, who served under Biden for two years, urged his campaign to show a “path to victory” despite the “overwhelmingly negative” polls.

Republican challenger Trump, 78, is meanwhile back on the warpath after a long interval of silence following the June 27 debate, accusing Biden of hiding secrets about his health.

“It’s the biggest cover-up in political history,” Trump thundered at a rally in Florida on Tuesday.

The former president dared his successor to another debate without moderators and challenged him to a round of golf.