LONDON -- Morgan McSweeney has resigned from his role of chief of staff to British Prime Minister Keir Starmer, as many members of Parliament blamed him for the appointment of Peter Mandelson to ambassador of the United States, Sky News reported Sunday.

"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," he said in a resignation letter published by local media.

"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," he added.

Starmer on Thursday apologized for his decision to appoint Mandelson as the ambassador, after fresh revelations about the former official's links to late American financier Jeffrey Epstein sparked political scandals in Britain.

Mandelson, 72, previously served as a senior cabinet minister under former prime ministers Tony Blair and Gordon Brown. He was appointed ambassador to Washington in early 2025 but was dismissed by Starmer after seven months as renewed questions about his past emerged.

Born in 1977 in Ireland, McSweeney moved to London at the age of 17 and began his political career in a junior Labour Party role under Tony Blair.