“It feels like an out of body experience, watching your party dying in slow motion,” the Labour MP told HuffPost UK.

He was speaking shortly after it was confirmed that Labour had come third in the Gorton and Denton by-election, a seat which the party won by nearly 13,500 votes barely 18 months ago.

To make matters worse, the Green Party came first, followed by Reform UK, an outcome polling expert Sir John Curtice described as “the worst possible result for the prime minister”.

“Can’t wait to hear how this is someone else’s fault,” said one MP. “If they try and blame the local operation or MPs, I’ll lose any respect I have for them.

“Polling day was incredibly well-run, but you can’t have a practical response to a crisis of leadership.”

Labour spent the past month insisting that only they could beat Reform, only for voters in the Manchester constituency to deliver an almighty raspberry to the PM.

If most Labour MPs hadn’t already decided that Starmer’s removal from office was a necessary first step for the party’s recovery, they certainly do now.

“He’s burying the Labour Party,” said one backbencher, succinctly.

Another senior figure told HuffPost UK: “Keir needs to be removed. The party has to act.”

Neil Duncan-Jordan told Times Radio: “If Keir Starmer is seen as a block when you go out and knock on doors – if people say to you, they’ll vote Labour, but they won’t vote Labour if he’s the leader – then he’s the block to us winning. And from a purely pragmatic, electoral strategic view, you have to remove that block

“Now, I’m not saying you do that this morning. I’m saying that we need to be serious about winning again. And, if there’s a block to winning again, then we need to look at how we remove that block.”

Fellow left-winger Clive Lewis said Starmer was “an interim prime minister”.

“How long that interim is will be up to the Parliamentary Labour Party,” he said. “He will not be here for very long, he does not deserve to be here much longer.”

Lewis, who said replacing Starmer with Blairite health secretary Wes Streeting would be “more of the same”, added: “We need a radical reset, fundamental change, or we will have a Reform government.

“And I’m afraid my colleagues and the rest of the party need to understand that.”

Even Angela Rayner, who has tended to keep her counsel since resigning as deputy prime minister last year, went public with a plea for Starmer to change course.

“This result must be a wake up call,” she said in a post on X. “It’s time to really listen – and to reflect. Voters want the change that we promised – and they voted for.

“If we want to unrig the system, if we want to make the change we were sent into Government to make, we have to be braver.”

The PM himself appeared deaf to the concerns of his colleagues, insisting that he will not change course and even suggesting that voters had been duped into backing the Greens.

In a letter to his fractious MPs, he said: “The Greens were able to capitalise on an endorsement from George Galloway to win over enough voters to push them over the line.

“Their willingness to welcome Galloway’s divisive, sectarian politics is a sign that the Greens are not the harmless environmentalists they pretend to be.”

“He looks ridiculous and totally disconnected,” said a Labour MP in response.

A Green source said: “Starmer is clearly coming to the end of his premiership, one that he has barely been clinging to. He has learnt nothing from the Greens’ stunning victory and once again he is tone deaf.

“His only answer now is to smear the voters as extremists who wanted the hope and change that he is failing to offer. It is not the election result or voters who are disappointing, it is his Labour government that is beyond disappointing.”

Starmer’s decision to block popular Manchester mayor Andy Burnham from standing to be Labour’s candidate also came in for criticism, but one party insider defended that decision.

He said: “Does anyone really believe Andy wouldn’t have invented his own foreign policy for the campaign, particularly after a week of knocking doors?

“That would have been the start of a leadership campaign before even being elected, which vindicates Keir’s decision even more.”

Another MP who was regularly on the doors in the constituency insisted the Burnham issue “was not mentioned once” by local voters.

The MP added: “We shouldn’t read much into the result. Lots of voters who would back us in a general election wanted to send a message to the party by voting Green.”

That view was echoed by Chris Hopkins, political research director at pollsters Savanta, who said “we need to be careful not to jump to too many conclusions, and I’d encourage Labour MPs not to overreact to this”.

He added: “Yes, it’s bad, but nothing that played out last night should come as a huge surprise, given the national polling and unpopularity of the government.

“While the temptation to act and publicly criticise Starmer having seen it play out for real at a by-election must be strong, this does need to not be the straw that breaks the camel’s back in terms of Starmer’s leadership of the party.

“Starmer must try to remain steadfast to his cause and maintain party discipline. He’s got to convince his own MPs that what happened last night is not an existential crisis, is not indicative of what could happen in their own seat at the next election and is just a by-election.

“Yes, the result is bad on paper but doesn’t really affect Labour’s parliamentary dominance, and could well be completely forgotten about in a few years time.”

Nevertheless, Hopkins conceded that Starmer will be in an “incredibly weak” position if May’s elections in Scotland, Wales and England are as bad as Labour MPs fear.

“His security is more down to the lack of an obviously challenger, especially while Burnham remains outside parliament, and I guess in that respect Starmer’s decision to block him running is probably remains the right one.

“Losing one by-election but keeping your closest rival on the outside looking in is probably an acceptable outcome.”

Unfortunately for Starmer, very few Labour MPs are as sanguine about the result as Hopkins.

The PM will limp on until May, largely because there is no time to replace him before then.

But a set of results even remotely as cataclysmic as Gorton and Denton will surely bring the curtain down on his ill-starred time in No.10.

Keir Starmer has lost his top civil servant barely a year after appointing him.

Cabinet Secretary Sir Chris Wormald agreed “by mutual consent” with the prime minister to stand down.

The prime minister hailed Chris Wormald’s “exceptional” leadership when he was announced as cabinet secretary in December, 2024.

However, it is understoof the PM has been unhappy with his performance and now he has gone just 14 months later.

In a statement, Wormald said: “It has been an honour and a privilege to serve as a civil servant for the past 35 years, and a particular distinction to lead the service as Cabinet Secretary.

“I want to place on record my sincere thanks to the extraordinary civil servants, public servants, ministers, and advisers I have worked with. Our country is fortunate to have such dedicated individuals devoted to public service, and I wish them every success for the future.”

The PM said: “I am very grateful to Sir Chris for his long and distinguished career of public service, spanning more than 35 years, and for the support that he has given me over the past year.

“I have agreed with him that he will step down as Cabinet Secretary today. I wish him the very best for the future.”

He is the third senior official to leave No.10 in the past week, after chief of staff Morgan McSweeney resigned on Sunday and communications director Tim Allan quit on Monday.

Wormald’s departure raises fresh questions about Starmer’s judgment following his decision to appoint Peter Mandelson the UK’s ambassador to Washington.

The disgraced former Labour peer was sacked seven months later over his connections to convicted paedophile Jeffrey Epstein.

Mandelson is now facing a criminal investigation over allegations he passed market sensitive information to the billionaire financier when he was business secretary in the wake of the 2008 financial crash.

Starmer sang Wormald’s praises when he first appointed him just over a year ago, saying: “Delivering this scale of change will require exceptional civil service leadership.

“There could be no-one better placed to drive forward our Plan for Change than Chris, and I look forward to working with him as we fulfil the mandate of this new government, improving the lives of working people and strengthening our country with a decade of national renewal.”

Speculation that Starmer himself could step down reached fever pitch on Monday after Scottish leader Anas Sarwar urged him to quit, but the prime minister told Labour MPs he was “not prepared to walk away”.

“I have had my detractors every step along the way, and I’ve got them now. Detractors that don’t want a Labour government at all, and certainly not one to succeed,” Starmer said at a Parliamentary Labour Party meeting.

“But I’ll tell you this, after having fought so hard for the chance to change our country, I’m not prepared to walk away from my mandate and my responsibility to my country, or to plunge us into chaos, as others have done.”