Mandelson saga will bring PM down unless he takes 'necessary action', Harman warns

Sir Keir Starmer risks being toppled by the fiasco around Lord Mandelson "unless he takes action", Baroness Harman has warned.

The former deputy Labour leader said the prime minister "seems to have drifted so far away from [his] values in appointing Peter Mandelson" to be US ambassador, and that he must return to them to survive.

It follows growing anger within the Labour Party at the PM's initial decision to oppose releasing documents about the vetting and appointment of Lord Mandelson, which led to a public climbdown last night in the Commons.

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Speaking to the Electoral Dysfunction podcast, Harriet Harman also warned the increasing angst around the PM's handling of Lord Mandelson is "so serious" and has called for Sir Keir's chief-of-staff, Morgan McSweeney, to go if he was behind the appointment.

Baroness Harman told Sky News' political editor Beth Rigby: "I think it is so serious for Keir Starmer. I don't think it's inevitable that it will bring him down.

"But it will bring him down - unless he takes the action, which is really necessary for him to take, and that's this: firstly, he's got to stop blaming Mandelson and saying, 'he lied to me'. Because actually he should never have been considering him in the first place.

"To say 'he lied to me' makes it look weak and naive and gullible. So it's just completely the wrong thing.

"He should be reflecting on why he made that appointment, not angry at the evilness of Peter Mandelson.

"He should also be thinking about a real reset in Number 10, because what you need from your team in Number 10 is people who share your values and your principles and who will help you be the best prime minister you can be, according to your true self.

"Clearly, that is not what happened because the Keir Starmer, who was DPP [director of public prosecutions], would never have appointed somebody like Peter Mandelson to represent the country."

The Labour peer also insisted that Sir Keir must "go back to the manifesto and do all the things that were promised in cleaning up politics and... bring them forward".

This includes bringing forward the government's action on tackling violence against women and girls, Baroness Harman said.

"If he does that, he can win the confidence of Labour backbenchers, the confidence in parliament and the confidence for the country," she said. "But I think that if he doesn't do that, there's no way this is going to be glossed over."

She added that she wants both the government and Sir Keir to succeed, and pointed out how she knew him well when he was the DPP.

Baroness Harman said: "If you'd asked me what he stood for, I would have said standing up for human rights, standing up to, for victims, standing up for women and girls. Standing up for decency and honesty.

"And yet he seems to have drifted so far away from those values in appointing Peter Mandelson to be the UK's representative in the US.

"Peter Mandelson was called the Prince of Darkness. It's not a secret that he was a bad person. I think that it is very, very serious for Keir Starmer because it goes to the values of the government."

You can listen to the full episode of Electoral Dysfunction here on Friday morning.

(c) Sky News 2026: Mandelson saga will bring PM down unless he takes 'necessary action', Harman warns