Marco Rubio, Donald Trump’s secretary of state, is said to have passed on his concerns about the appointment to the British Government last year.
The Telegraph understands that Morgan McSweeney, Starmer’s chief of staff, was also warned twice about the peers’ links to Epstein by the Cabinet Office.
Last night, Parliament’s Intelligence and Security Committee (ISC), which is overseeing the release of documents linked to Mandelson’s appointment, demanded to see uncensored files.
‘I’ve never seen him this angry’
Downing Street issued a statement saying “transparency” is important but did not announce its decision, though it is understood No 10 is preparing to approve the request.
A Cabinet minister called for maximum disclosure, telling The Telegraph: “I think he’s got to publish as much as he can as soon as possible, allow the ISC to do their job and try to focus on the things that need doing.
“He needs to be completely open about what he knew and when.”
The source also said of the Prime Minister’s mood: “He’s furious. I’ve never seen him like this before, just how angry he is.”
Mandelson, who is now facing a criminal investigation over whether leaking sensitive information to Epstein amounted to misconduct in office, is expected to be interviewed by police within days.
Speaking before the press, Starmer issued a rebuke of Mandelson and indicated that the vetting process, partly done by security figures, had been proven to be flawed.
Starmer said Mandelson had lied to his team about his friendship with Epstein during the vetting process, claiming the peer suggested he “barely knew” the paedophile.
Starmer said: “It had been publicly known for some time that Mandelson knew Epstein. But none of us knew the depth and the darkness of that relationship. What has come to light has raised serious questions, information that was not known at the time of his appointment.”
On vetting, the Prime Minister said: “Clearly, both the due diligence and the security vetting need to be looked at again. I’ve already strengthened the due process, I think we need to look at the security vetting.”
Starmer apologised to the victims for making Mandelson the US ambassador last February. He was sacked in September over an earlier release of Epstein files.
Starmer said he regretted the appointment, would never have made it if he knew what he knows now, and said he was “angry and frustrated” with the peer’s lies.
But Labour MPs and grandees publicly questioned Starmer’s judgment, given it was known at the time of the appointment that Mandelson had been close to Epstein. Photographs of them together were already in the public domain.
Harriet Harman, a former Labour deputy leader and a figure from the party’s moderate wing, told Sky News: “To say ‘he lied to me’ makes it look weak and naive and gullible. So it’s just completely the wrong thing.”
On whether the Prime Minister will be toppled over the scandal, she added: “If he doesn’t take the path which is necessary, yes, this will finish him off.”
Some Labour MPs also suggested the Prime Minister should resign.
Ian Byrne, the MP for Liverpool West Derby, told Times Radio: “I think the Prime Minister is a man of honour and I think potentially he’ll reflect on his position once we get the full details, once that information is released and that decision is taken.”
Barry Gardiner, the Labour MP for Brent West, said when asked if Starmer should step down that he must “think very hard about what’s in the country’s best interest”.
Another Labour MP told The Telegraph: “The question is, can Keir Starmer make it through to the weekend at the moment?”
Others played down the prospect of any imminent change of leadership, turning their fire instead on McSweeney, who was instrumental in Mandelson’s appointment as US ambassador, and demanding his sacking.
One government minister told The Telegraph: “Things are existential. Something needs to change and Morgan going is the bare minimum.”
Karl Turner, the MP for Hull East, told the BBC: “If the PM decides he has to be surrounded by advisers who give him shoddy advice, the reality of that is the Prime Minister is going to have to make a decision about his future at some point soon. If McSweeney is still in 10 Downing Street, the PM is up against it.”
Some figures in the Cabinet are closely watching how the scandal is playing on the doorstep as they head back to their constituencies this weekend and talk to voters.
Defeat for Labour on February 26 at the Gorton and Denton byelection, at which Andy Burnham, the Greater Manchester Mayor, was blocked from standing, could become a flashpoint for those Labour MPs discontented with the Prime Minister.
One government minister, discussing Starmer’s chances of continuing as leader, said: “The only way any of this could be resolved is if the Cabinet decided to move.”
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