Sir Keir Starmer's chief of staff Morgan McSweeney has stepped down amid mounting pressure over the Lord Mandelson controversy.
The Prime Minister's top adviser faced increasing criticism after he recommended the peer for the role of US ambassador.
His departure follows Sir Keir's recent accusation that Lord Mandelson betrayed Britain and was dishonest about his connections to Jeffrey Epstein.
The loss of his longtime adviser will come as a blow to Sir Keir, whose own political future has been thrown into jeopardy amid questions of his judgment in picking Lord Mandelson as his top diplomat in Washington.
Sir Keir credited Mr McSweeney’s “dedication, loyalty and leadership” for Labour’s 2024 general election win, as he expressed a “debt of gratitude” in a statement that did not mention the Lord Mandelson fiasco.
In his exit statement, Mr McSweeney said the decision to appoint Lord Mandelson to the job was “wrong”, and that he took “full responsibility” for advising Sir Keir to go ahead.
He also called for an overhaul of the vetting procedures, which apparently failed to disprove what No 10 has called Lord Mandelson’s “lies” about barely knowing Epstein.
The peer was sacked last year over his relationship with the notorious paedophile, but anger in Westminster has intensified after the latest release of documents showed he leaked information to his friend while he was a government minister.
Mr McSweeney said: “After careful reflection, I have decided to resign from the Government. The decision to appoint Peter Mandelson was wrong. He has damaged our party, our country and trust in politics itself.
“When asked, I advised the Prime Minister to make that appointment and I take full responsibility for that advice. In public life responsibility must be owned when it matters most, not just when it is most convenient. In the circumstances, the only honourable course is to step aside.
“This has not been an easy decision. Much has been written and said about me over the years but my motivations have always been simple: I have worked every day to elect and support a government that puts the lives of ordinary people first and leads us to a better future for our great country. Only a Labour government will do that.
“I leave with pride in all we have achieved mixed with regret at the circumstances of my departure. But I have always believed there are moments when you must accept your responsibility and step aside for the bigger cause.
“As I leave I have two further reflections:
“Firstly, and most importantly, we must remember the women and girls whose lives were ruined by Jeffrey Epstein and whose voices went unheard for far too long.
“Secondly, while I did not oversee the due diligence and vetting process, I believe that process must now be fundamentally overhauled. This cannot simply be a gesture but a safeguard for the future.
“I remain fully supportive of the Prime Minister. He is working every day to rebuild trust, restore standards and serve the country. I will continue to back that mission in whatever way I can. It has been the honour of my life to serve.”
Sir Keir said: “It’s been an honour working with Morgan McSweeney for many years. He turned our party around after one of its worst ever defeats and played a central role running our election campaign. It is largely thanks to his dedication, loyalty and leadership that we won a landslide majority and have the chance to change the country.
“Having worked closely with Morgan in opposition and in government, I have seen every day his commitment to the Labour Party and to our country. Our party and I owe him a debt of gratitude, and I thank him for his service.”
Tory leader Kemi Badenoch welcomed Mr McSweeney’s departure, but said the Prime Minister should “take responsibility” for his actions.
She said on X: “It’s about time.
“But once again with this PM it’s somebody else’s fault: ‘Mandelson lied to me’ or ‘Morgan advised me’.
“Keir Starmer has to take responsibility for his own terrible decisions. But he never does.”
