Keir Starmer was desperately clinging on to power after mounting calls for him to quit as his party erupted in open mutiny. Labour’s Scottish leader Anas Sarwar put the “final nail in the coffin” by holding a hastily arranged press conference to tell the Prime Minister he must go.

And in a day of high drama, Health Secretary Wes Streeting accused No 10 of briefing against him again at the same time as he was giving an interview expressing support for the beleaguered PM. Sir Keir was left pleading for his future at a meeting of mutinous Labour backbenchers tonight.

Mr Sarwar, the party’s Scottish leader since 2021, warned: “The leadership in Downing Street has to change.”

Andrew Bowie, shadow Scottish secretary, said: "Anas Sarwar has just put one of the final nails in Starmer's political coffin. The Prime Minister’s credibility is shot. Scottish Labour MPs should put Keir Starmer out of his misery.”

Mr Sarwar’s dramatic statement came hours after Sir Keir was rocked by the resignation of his Downing Street communications chief Tim Allan and just a day after the Prime Minister’s chief of staff Morgan McSweeney quit. He left the Number 10 team amid fury over the appointment of Peter Mandelson as ambassador to the US.

Conservative leader Kemi Badenoch insisted Sir Keir must resign “if he can’t do the job”.

She said: “It’s quite clear that Keir Starmer does not have a grip on his Government. He is in office, but not in power, and our country is not being governed.

“The Labour Party have a huge majority, but can’t run anything. They need to decide who is the best person to lead their party so that they can fix the problems of this country. What I’m seeing is a Government that is completely adrift. The Prime Minister is blowing around like a plastic bag in the wind. If he can’t do the job, then yes, he should go.”

The Prime Minister’s Cabinet colleagues rallied around their embattled Labour leader in an orchestrated show of support.

But Labour MPs are furious over his decision to appoint Lord Mandelson as US ambassador despite knowing that his links with Jeffrey Epstein continued after the financier’s conviction for child sex offences. Downing Street insisted the Prime Minister would not resign.

A spokesman said: “Keir Starmer is one of only four Labour leaders ever to have won a general election. He has a clear five-year mandate from the British people to deliver change, and that is what he will do.”

And Sir Keir’s Cabinet colleagues launched a desperate attempt to shore up his position. Deputy Prime Minister and Justice Secretary David Lammy came out to back Sir Keir first, followed by Chancellor Rachel Reeves.

Mr Streeting, a possible leadership hopeful, told Sky News’ Electoral Dysfunction podcast “no” when asked whether Sir Keir needs to resign. He said it “has not been the best week for the government” but urged Labour MPs to give Sir Keir a chance.

But his spokesman later said: “At the same time as Wes was in an interview saying that Keir needed a chance to set out his case and his plan, No 10 were briefing that Wes had told Anas Sarwar to make his statement. This is the problem.”

Meanwhile former deputy prime minister Angela Rayner, also considered a leadership threat to Sir Keir, issued statements backing the Prime Minister.

She said: “The recent scandal around Peter Mandelson and Jeffrey Epstein was shocking – and demands that both this Government and our party learn the lessons, and act on them.

“But the worst possible response would be to play party politics or factional games. Labour is only getting started on changing things for the better – our Employment Rights Act, renters’ rights, leasehold reform, free school meals and lifting kids out of poverty. I urge all my colleagues to come together, remember our values and put them into practice as a team. The Prime Minister has my full support in leading us to that end.”

Sir James Cleverly, shadow communities secretary, said the Cabinet was united behind a single message - “we don’t want a leadership change this side of the local elections, we want Starmer to carry the can and then stand down”.

Meanwhile, Mr Allan’s resignation means Starmer will now be forced to appoint a fifth director of communications in little more than 18 months. It follows the decision of Sir Keir’s chief of staff Morgan McSweeney stepping down on Sunday following his involvement in Mandelson’s appointment.

Mr Allan said he was standing down to allow “a new No 10 team to be built”. The former adviser to Sir Tony Blair’s government was appointed in September to improve communications across his administration.

In an address to No 10 staff yesterday (MON) morning, Sir Keir said: “We must prove that politics can be a force for good. I believe it can. I believe it is. We go forward from here. We go with confidence as we continue changing the country.”

He said they are united by a “driving purpose” of “public duty”. Speaking to his team about the decision to appoint Lord Mandelson to the UK’s highest diplomatic role, he said: “The thing that makes me most angry is the undermining of the belief that politics can be a force for good and can change lives.

“I have been absolutely clear that I regret the decision that I made to appoint Peter Mandelson. And I’ve apologised to the victims which is the right thing to do.”

The Prime Minister is expected to speak to women Labour MPs after Prime Minister’s Questions on Wednesday. He and Mr McSweeney have pinned the blame on vetting by the security services for failing to disprove Lord Mandelson’s claims that he barely knew the late financier, which were later dramatically debunked by disclosures in the so-called Epstein files.

Officials have been tasked with examining that process as a priority. In another dramatic development, Mr Streeting published some of his private WhatsApp messages with Mandelson in apparent attempt to draw a line under their friendship.

In one, he suggested the government had "no growth strategy at all" after Mandelson complained about the economic philosophy.

The Health Secretary also agreed with Mandelson’s comment that “the government problems do not stem from comms”, suggesting the issue was the PM himself. Mr Streeting insisted he has "nothing to hide" over his relationship with Mandelson, adding “I’m embarrassed to have known” him.

It comes as police last week searched Mandelson’s two properties as part of a criminal investigation. The disgraced former peer is being probed as part of enquiries into misconduct in public office offences.

The Epstein Files indicated Mandelson leaked market-sensitive information to his friend while he was Business Secretary. Andrew Mountbatten-Windsor also allegedly shared confidential reports from his role as the UK’s trade envoy with Jeffrey Epstein, newly released emails revealed.