Labour MPs have warned that Keir Starmer’s leadership is under serious threat following intense backlash over the appointment of Peter Mandelson as ambassador to the USA. Fury erupted after Starmer admitted he was aware of Mandelson’s past friendship with convicted sex offender Jeffrey Epstein before approving the appointment. A Commons debate nearly ended in government defeat, narrowly avoided through a last-minute amendment forcing the future release of documents relating to Mandelson’s vetting and appointment. Several Labour MPs described a collapse of trust, with some openly questioning whether they could support Starmer in a confidence vote. The mood, described as 'dark' and 'terminal’, has unsettled even long-standing loyalists. MPs warned that once withheld documents are released - currently delayed by a Metropolitan Police investigation - a leadership challenge could follow. Though Starmer has pledged transparency and announced plans to strip Mandelson of honours, and ministers insist he acted in good faith, many MPs fear lasting damage to the government’s credibility and moral authority.