Morgan McSweeney tendered his resignation on Sunday, stepping down from his role as the chief of staff for British Prime Minister Keir Starmer. His departure comes as criticism intensifies over his involvement in recommending Peter Mandelson for the position of the United Kingdom’s ambassador to the United States.

In a statement shared with The Guardian, McSweeney admitted that appointing Mandelson was a “mistake” and took full accountability for this recommendation. He described his resignation as the only honorable action under the circumstances.

McSweeney expressed that Mandelson’s actions had inflicted harm on the party, the nation, and public trust in politics. He acknowledged that making the decision to step down was challenging.

Highlighting the erosion of public trust due to the controversy, McSweeney called for a comprehensive overhaul of the government’s vetting and due-diligence procedures. Despite his resignation, he affirmed his ongoing support for Starmer and the Labour government’s initiatives.

Downing Street’s former Chief of Staff, Morgan McSweeney, was seen attending the annual Lord Mayor’s Banquet at Guildhall in London on December 1, 2025. (Chris J. Ratcliffe/Reuters)

Documents and emails released by the Justice Department in January revealed that Mandelson had maintained contact with Jeffrey Epstein even after Epstein’s 2008 conviction on charges of soliciting prostitution, including one case involving a minor.

The Associated Press reported that newly surfaced documents indicate Mandelson may have passed along sensitive government information to Epstein in the period following the 2008 global financial crisis.

The outlet also cited documents and financial records indicating Epstein transferred a total of $75,000 in 2003 and 2004 to accounts connected to Mandelson or his husband, Reinaldo Avila da Silva.

British Prime Minister Keir Starmer, right, talks with Britain’s ambassador to the United States Peter Mandelson during a welcome reception at the ambassador’s residence in Washington, on Feb. 26, 2025. (Carl Court/Pool Photo via AP)

Foreign Office minister Stephen Doughty told the House of Commons on Sept. 11 that Starmer asked him to withdraw Mandelson as the UK’s ambassador to the United States after emails showed Mandelson’s relationship with Epstein was “materially different” from what was known at the time of his appointment.

“In particular, Lord Mandelson’s suggestion that Jeffrey Epstein’s first conviction was wrongful and should be challenged is new information,” Doughty said. “In the light of that and mindful, as we all are, of the victims of Epstein’s appalling crimes, Lord Mandelson has been withdrawn as ambassador with immediate effect.”

Mandelson resigned from the Labour Party on Feb. 1.