Labour MPs have warned that Keir Starmer’s days as prime minister are numbered after a day of fury over the appointment of Peter Mandelson as US ambassador despite his friendship with Jeffrey Epstein.The government was on the brink of a defeat in the Commons until a mid-debate amendment brokered by Meg Hillier and Angela Rayner to force the release of documents about Mandelson’s appointment and the depth of his relationship with the convicted child sex offender.MPs said the eventual release of the documents – which may be delayed by a police investigation into Mandelson – could trigger a leadership challenge.“We need all the poison to come out,” one MP said.One former minister said: “We’ve had a lot of bad days recently, but this is the worst yet, I think,” while another MP warned: “Trust is finite.

I’m personally not sure I could trust myself to back the prime minister in a confidence vote,”“The most terminal mood is among the super-loyal,” an MP from the 2024 intake noted,MPs said that Starmer’s admission at prime minister’s questions that he had known about Mandelson’s friendship with Epstein before his appointment was a clarifying moment,“You could feel the atmosphere change; it was dark,” one MP who had previously been close to Starmer said,No 10 said afterwards that the prime minister was only aware of what was already in the public domain.

“It’s just indefensible,” said one backbencher,“They knew all about Peter’s relationship with Epstein but gave him the job anyway,“It’s like Chris Pincher on steroids,” they added, referring to the scandal that eventually brought down Boris Johnson,“The moment Keir admitted it then that was it – it’s over,”Another former minister said: “We were meant to be the ones who didn’t do this stuff.

It’s time for a fresh start, the sooner the better,”Several MPs said the prime minister’s chief of staff, Morgan McSweeney, who had been close to Mandelson, should take responsibility for the failures and resign,“The government is on the run,” another MP said,“Goodness knows what will come out – there could be a lot of red faces and departures off the back of it,”No 10 had said it hoped the documents would prove that Mandelson had lied about the depth of his relationship with the disgraced financier.

But on Wednesday night, the Metropolitan police said it had blocked the release of certain documents in case they prejudiced a criminal investigation in Mandelson’s apparent sharing of confidential government documents with Epstein.Earlier Downing Street attempted to mitigate the Conservatives’ bid to trigger the release of the documents by adding exemptions for national security and to protect international relations.MPs called the move a “cover-up” and demanded the judgment be made by the intelligence and security committee of MPs – rather than the cabinet secretary – over what to release.Whips were warned they were on the brink of losing the vote as Hillier and Rayner rose in the Commons to argue for the role of the select committee – and were forced to draft a second amendment to appease MPs.Rayner, the former deputy prime minister, is understood not to have been planning to speak in the debate, but cancelled a lunch meeting when she realised intervention was needed to stop a potential government defeat.

After her speech in the chamber, she spoke to the chief whip and leader of the house to broker the amendment, along with Hillier.“Yet again the prime minister has to thank Angela Rayner’s swift political judgment to save this government from itself,” said one MP, referring back to the concessions brokered by Rayner before the welfare reform vote.Backing Rayner for a leadership bid, they said: “The sooner the day comes that she’s making the original decisions, the better.”Another MP said: “If Angela didn’t have her tax investigation ongoing, she’d be getting numbers [for a leadership challenge] offered to her tonight.”One Labour backbencher called the day’s events a “bin fire”, but said that while there was a lot of heat and noise behind the scene few Labour MPs and no ministers were yet willing to put their heads above the parapet.

“I think if Ange had said something it would be game over,” they said.“The PM is safe for now.”Cabinet ministers expressed annoyance at the handling of the amendments, with one saying it had been “frustrating”.Another said they had warned the Cabinet Office over how it would look to attempt to mitigate the Tory motion – and said the priority should have been to avoid any move that could be interpreted as a cover-up.Several MPs told the Guardian that it would be “ironic” if Starmer was forced out over Mandelson’s links to Epstein, as they were convinced of his personal commitment to tackling violence against women and girls.

“We’ve never had a PM that cares so much about it,” said one.“It would be mad if another man being mates with a paedophile brought him down, but it’s totally possible.”The motion to release the documents relating to Mandelson’s appointment passed on Wednesday night and No 10 said it would comply as soon as possible, in accordance with police advice.“We will comply with the motion, including publishing documents relating to Peter Mandelson’s appointment, which will show the lies he told,” a spokesperson said.The best public interest journalism relies on first-hand accounts from people in the know.

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Our guide at theguardian.com/tips lists several ways to contact us securely, and discusses the pros and cons of each.The Met said that it had “advised that the release of specific documents could undermine our current investigation.We therefore asked them not to release certain documents at this time.“Going forward as material is made available to us, and if we identify further documents that we believe could prejudice our investigation, we will continue to ask the government to pause their release until such time as the risk of prejudice no longer exists.

The integrity of our investigation is paramount to securing justice.”Starmer said at PMQs that he would soon move legislation to make it easier to strip peers of their titles – including Mandelson.He said he had also asked King Charles to remove him from the list of privy counsellors.But he admitted during the exchanges that he had been aware of Mandelson’s friendship with Epstein, suggesting the peer had lied during the first stage of the vetting process about the depth of the friendship.No 10 said Starmer was referring only to what was in the public domain.

“This was looked into as part of the appointment process as the prime minister referenced today,” the source said.“Peter Mandelson lied to the prime minister, hid information that has since come to light and presented Epstein as someone he barely knew.”Starmer will attempt to move back on to his domestic agenda on Thursday in a speech about the government’s “Pride in Place” scheme, intended as a replacement to the Conservatives’ levelling up agenda.Starmer believes the plan to invest £5bn over 10 years in more than 300 deprived areas will help dent the threat from Reform UK.The fund is meant to pay for regeneration efforts such as patching up derelict shops, pubs and libraries.

The prime minister will announce on Thursday an extra £800m for the scheme, which will allow an additional 40 places to access funding, saying: “If you want to know where hope lives in Britain – it is in our communities, that is where people come together,”