Sir Keir Starmer faces a vote from MPs on whether to launch a sleaze inquiry into the Peter Mandelson vetting saga on what will be a crucial day for the future of his premiership.
Sir Lindsay Hoyle confirmed on Monday that MPs would be allowed to debate whether or not the prime minister should be referred to the powerful Commons Privileges Committee for a probe into whether he misled parliament over the disgraced peer’s appointment as US ambassador.
The committee was responsible for Boris Johnson’s exit from frontline politics after it investigated him for misleading the House over the “partygate” breaches of Covid laws in Downing Street.
It will come on the same day ashis former chief of staff Morgan McSweeney and former top civil servant Sir Philip Barton – both of whom played key roles in the appointment of Lord Mandelson – will give evidence to the Foreign Affairs Committee.
Mr McSweeney was widely regarded as a protege of the former US ambassador and pushed for his appointment, while Sir Philip was the predecessor of Sir Olly Robbins – who was sacked by Sir Keir for failing to tell ministers that Lord Mandelson had failed security vetting.
Sir Philip left the department in January 2025, eight months earlier than expected. The committee is expected to examine whether he left his post as a result of his opposition to Lord Mandelson’s appointment.
As the prime minister faces pressure from all sides on the Mandelson saga, he will also have his attention diverted by a meeting of the Middle East Response Committee, as part of an attempt to mitigate the economic impacts of the Iran war, and by King Charles’s address to the US Congress, both of which are taking place on Tuesday.
On the same day, the Commons will vote on whether to refer the PM to the Privileges Committee to consider if he misled MPs when he claimed “due process” was followed in Lord Mandelson’s appointment, and that there was “no pressure whatsoever”.
It comes after it emerged that the Foreign Office decided to appoint the Labour grandee despite the fact that he failed the vetting process.
The prime minister repeatedly told MPs that he and his ministers only found out that UK Security Vetting had advised Lord Mandelson should be denied clearance for the role last Tuesday evening, despite The Independent raising concerns that he had failed vetting last September and running a front page story on it – prompting claims of a cover-up.
Labour’s huge majority in the Commons means such a vote would almost certainly not pass, especially as Labour MPs are expected to be whipped to vote against the motion, but it could still be damaging for the prime minister.
As first revealed by The Independent, MPs from both sides of the House, including Labour, are understood to have written to the speaker requesting that the committee, which deals with serious disciplinary issues in parliament, investigate the PM.
In the wake of Sir Lindsay’s decision to allow MPs to debate the issue, Tory leader Kemi Badenoch claimed that the “facts are overwhelming”.
“The prime minister misled the House of Commons, repeatedly,” she claimed. “He appointed a national security risk and friend of a convicted paedophile, to be our ambassador in Washington, our most sensitive diplomatic post. He pretended that full due process was followed for this appointment. It was not.”
Ms Badenoch argued that the prime minister must “be held to the same standards he held previous prime ministers to”, warning: “There is no room for hypocrisy.”
She added: “Every MP now faces a matter of conscience, not party, conscience. Do they cover this up or do they vote to seek the truth?”
But a No 10 spokesperson dismissed the attempt to launch a parliamentary inquiry as a “desperate political stunt by the Conservative Party”.
A number of MPs and former parliamentarians have referred to the precedent set during the Partygate probe into Mr Johnson, when the Tories failed to use their majority to oppose the inquiry, and their MPs on the committee “put party second” in finding him guilty.
It comes as concerns grow among Labour MPs across different factions of the party that the government plans to whip to block the vote.
However, the Tories are going to push the fact that they did not oppose the motion when Boris Johnson was referred to the committee for misleading parliament.
One former Cabinet minister said: “We did set something of a precedent, but I think we have some moral authority on the issue because of the way we allowed the inquiry to take place into Boris. This is a question of putting integrity before party.”
Sir Ed Davey also piled pressure on Sir Keir not to whip his MPs to oppose his referral to the Privileges Committee, saying: “Even Boris Johnson didn’t block his MPs voting for scrutiny.
“MPs must be given a free vote on any motion to refer Starmer, not forced into being accomplices to a cover-up.”
Over the weekend, Cabinet minister Darren Jones insisted there is “no case to answer” when asked about a potential referral of Sir Keir to the committee, as well as accusing the Conservatives of “using tactics” ahead of local elections.

