It took a famous TV doctor to diagnose the patient. After two weeks of turmoil in the US Democratic party over President Biden’s re-election bid, it was ER’s Doug Ross, AKA George Clooney, who wrote up a devastating evaluation of the incumbent president.

The 63-year-old actor was not in theatrical mode when he wrote a more-in-sorrow letter published by the New York Times last week that called on Biden to withdraw from the presidential race that the White House reportedly begged him not to submit, coming three weeks after Clooney helped raise $30m for the Biden-Harris ticket at a lavish Hollywood fundraiser.

But Clooney’s bedside manner was impeccable: “I love Joe Biden. As a senator. As a vice-president and as president. I consider him a friend, and I believe in him,” he wrote. “But the one battle he cannot win is the fight against time. None of us can.”

Clooney was speaking for ­himself – and for a large swathe of liberal-leaning Hollywood donors angry at what they see as White House deception over the apparent decline of Biden’s health. Clooney said the man at the fundraiser “was the same man we all witnessed” in his debate performance two weeks later.

In the current spirit of panic and recrimination, with a White House press corps turning every Biden appearance into a test of competence, Democrat money bundlers, including co-chair of Biden’s re-election campaign and movie producer Jeffrey Katzenberg, are under suspicion of helping to cover up Biden’s apparent health issues.

Clooney’s letter has put the Ocean’s Eleven actor out of political harm’s way. The Democratic party may not be so lucky. Democrats, says James Carville, the Clinton strategist who last week called for a blitz primary to select a new candidate, “are hellbent on a mission to force the American people to do something they don’t want to do – to vote for Joe Biden”.

“George has come out, [former house speaker] Nancy Pelosi has come out – I don’t know what else people can do,” Carville told the Observer. “Other than a few people in Congress, everybody thinks this is a terrible idea [for Biden to run]. But you’re up against a guy who doesn’t want to leave, and that’s just where we are.”

George Clooney is not the only Clooney making waves on a global stage. Last month his wife Amal Clooney was revealed to have played an important role in making the case for arrest warrants to be issued by the international criminal court (ICC) to Israeli prime minister Benjamin Netanyahu, defence minister Yoav Gallant and three top Hamas leaders.

Biden called the ICC move “outrageous” and said that whatever the ICC prosecutor might imply, “there is no equivalence – none – between Israel and Hamas”. According to the Washington Post, George Clooney called Steve Ricchetti, counsellor to the US president, to protest about the administration’s willingness to impose sanctions in which his wife could get caught.

This week, the Biden-Harris campaign attempted to blame Clooney’s letter on “pre-existing tensions” – hinting at the ICC dust-up. A Hollywood producer familiar with the couple told the Observer that the White House’s explanation for the letter was “bullshit” and the lawyer had been smeared because her work is on human rights irrespective of political division.

“George has power in Hollywood. Amal doesn’t, except as George’s wife,” they added. “Her power is in the UK, at the Hague and on the pages of Vogue.”

The lawyer has not commented on her husband’s political intervention, which may have come with Barack Obama’s tacit approval. But after 10 years together, George and Amal Clooney are seen as one of the most stable couples in Hollywood.

They’d met at the actor’s home in Lake Como, Italy, when a mutual friend brought her by. Clooney’s agent had also got wind of the ­introduction, the actor later revealed. “My agent said: ‘I met this woman who is coming to your house, who you’re going to marry.’ It really worked out that way.”

“It felt like the most natural thing in the world,” Amal said. “I always hoped there could be love that was overwhelming and didn’t require any weighing or decision-making.”

A safari in Kenya to see giraffes sealed the deal. In 2014 he proposed, they married in Venice and now have twins.

The political instinct which had surfaced in Clooney films including Good Night, and Good Luck (2005) and The Ides of March (2011), soon took flight. By 2016 the couple were meeting with then-German chancellor Angela Merkel to talk refugee policy; that year they were at a UN refugee summit and soon after established the Clooney Foundation for Justice, which focuses on legal rights for those targeted by oppressive governments, tracking the money of human rights abusers and those profiting from war crimes.

“We’re both inspired by the young people out there challenging injustice in their communities, a new generation that won’t accept the status quo,” the actor said in an awards acceptance speech two years ago.

But Clooney’s intervention comes with potential costs. The Bidens, like the Clintons and Obamas, may see themselves as benefiting from rubbing shoulders with celebrities, but the intersection of entertainment and politics, and the money and ideologies that underpin it, is repulsive to many outside political-entertainment enclaves. In an echo of Trump, Biden now says the rising chorus against him is coming from members of “the elites”, despite the bad timing of first lady Dr Jill Biden appearing on the cover of the August US Vogue.

The tradition of celebrity-political endorsements goes back to Frank Sinatra, who organised his friends, the Rat Pack, to campaign for John F Kennedy. Two decades later, disagreements over Ronald Reagan forced celebrities to choose where they belonged.

“That’s where we are still,” explains veteran Democrat strategist Hank Sheinkopf. “Celebrities see themselves as an important part of the Democratic fundraising and thought-based operation, which a lot of Americans would not agree with.”

Sheinkopf says that the fight over Biden’s future is as much about the future of the Democratic party as it is about Biden’s health – and Clooney’s intervention will make Maga Republicans fight harder for candidate Trump.

“Democrats are the party of the elites despite the fact that they see themselves as the party of the non-elites,” he says. Regardless of who is writing the cheques – Hollywood celebrities or a rightwing Texas industrialist – “what all elites want is a party that does what they want because they think it’s right”.

“But that’s not who Joe Biden is. He represents the old pro-union, almost colour-blind left, but that’s not who the operators behind the scenes are,” he adds.

Peter Bart, previous editor of the Hollywood trade bible Variety, wrote in a Deadline column that he had “great respect for Clooney’s decision” but it was also one that “will cost him”.

He recalled other Hollywood stars who had mixed politics with entertainment, including Jane Fonda, Charlton Heston and John Wayne. “Apart from potential career damage, Clooney must confront donors who have spent millions at his ­urging to support a ticket he now renounces,” Bart, 91, warned.

He recalled a conversation he’d had with Ronald Reagan about Nixon. “I want people to like me, even voters who vote against me,” Reagan told him. “Nixon doesn’t seem to care, but I’m still an actor.”

Still, Clooney’s intervention has set him up for criticism. The progressive left and African-American voters, both voting blocs Biden is courting to firm up his support, slammed the actor for taking a position afforded him by being famous, white and male.

Others have implied that perspectives are different from the window seat of a Gulfstream jet flying between homes in Los Angeles, England, France and Italy. (Besides being a successful actor, known for pranking friends, Clooney and partner Rande Gerber, husband of Cindy Crawford, split up to $1bn from the sale of their tequila brand Casamigos.)

Clooney has been criticised, too, from the other side. Trump weighed in, saying Clooney “turned on Crooked Joe like the rats they both are”, and some have questioned why Clooney, and Hollywood more broadly, waited until after the debate to disclose what they had witnessed at the fundraiser.

Still, the New York Times letter establishes the Kentucky-born actor as a modern-day Warren Beatty, the actor who made his political beliefs part of his public image. Beatty never ran for office and quipped it would be “more like running for crucifixion”, nor has Clooney, allowing both to ride over the humdrum day-to-day of retail politics.

“George’s op-ed was provocative, well done, but voters don’t want this anyway: 73% of the voting public say they want something different,” says Carville. “They’re not asking for anything difficult – just a different nominee. We’re in a crisis.”