Morgan McSweeney has stepped down as Keir Starmer's chief of staff. He resigned after advising the prime minister to appoint Peter Mandelson as the UK's ambassador to the United States, a move he later described as a mistake that caused significant harm. McSweeney said he took full responsibility for the recommendation and believed that resigning was the right thing to do. In response, Starmer thanked McSweeney for his work and noted that he played a vital role in leading the party to its election victory.