British Prime Minister Keir Starmer’s chief of staff resigned on Sunday due to the furor over the appointment Peter Mandelson as UK ambassador to the US despite his links to Jeffrey Epstein.

Morgan McSweeney said he took responsibility for advising Starmer to appoint Mandelson, 72, to Britain’s top diplomatic post in 2024.

“The decision to appoint Peter Mandelson was wrong. He has damaged our party, our country and trust in politics itself,” McSweeney said in a statement. “When asked, I advised the Prime Minister to make that appointment and I take full responsibility for that advice.”

Starmer is facing a political firestorm and questions about his judgment after the recently released documents, in part a large treasure trove of Epstein files published in the United States, suggested that Mandelson sent market-sensitive information to a convicted sex offender while he was the UK government’s business secretary during the 2008 financial crisis.

The Prime Minister apologized last week for “believing Mandelson’s lies”. He said that “none of us knew the depth of darkness” of the relationship between Mandelson and Epstein when the former was vetted for the diplomatic job.

“Mandelson betrayed our country, our parliament and my party … he repeatedly lied to my team when asked about his relationship with Epstein before and during his time as ambassador. I regret nominating him,” Starmer told MPs last week.

The Starmer government has promised to release its own emails and other documents relating to Mandelson’s appointment, which it says will show Mandelson misled officials.

A number of MPs called on Starmer to resign.

“Keir Starmer must take responsibility for his terrible decisions,” said Kemi Badenoch, leader of the opposition Conservative Party.

Mandelson, a former cabinet minister, ambassador and senior statesman in the ruling Labor Party, has not been arrested or charged.

The The Metropolitan Police are now investigating and officers searched Mandelson’s London home and another property linked to him on Friday. Police said the investigation was complex and would require a “significant amount of further collection and analysis of evidence”.

Starmer had dismissed Mandelson in September from his job as ambassador due to earlier revelations about his ties to Epstein. But critics say emails recently released by the US Justice Department have brought serious concerns about Starmer’s sentencing to the fore. They claim he should have known better than to appoint Mandelson in the first place.

The new revelations include documents suggesting Mandelson shared sensitive government information with Epstein after the 2008 global financial crisis. They also include records of payments totaling $75,000 in 2003 and 2004 from Epstein to accounts linked to Mandelson or his husband Reinaldo Avila da Silva.

Apart from his association with Epstein, Mandelson has twice previously had to resign from high government posts over money or ethics scandals.