A rift has cracked open at the heart of Sir Keir Starmer’s government over his appointment of Lord Peter Mandelson as British ambassador to Washington, with senior ministers openly accusing the prime minister of fostering a toxic “them and us” divide between Number Ten and the civil service. The atmosphere inside the cabinet, according to one senior government source, is now “bleak”, and the sense that “the wheels have stopped” suggests a loss of momentum that threatens to define the early months of Starmer’s premiership. Viewed from Westminster, this is not merely a row about diplomatic protocol; it is a test of whether the prime minister can command the loyalty of his own top team when the political weather turns foul.

The backlash is not confined to the cabinet room. Labour backbenchers, particularly those representing the party’s Red Wall seats, have been blunt in their condemnation. Jo White, who chairs the Red Wall group of MPs, described the Mandelson appointment as Starmer’s “biggest mistake” and urged the government to “cleanse” itself of the vetting scandal. Her constituents, she noted, remain fixated on the cost-of-living crisis rather than ambassadorial intrigue, but the disconnect between Westminster’s preoccupations and voters’ daily concerns only amplifies the sense of a government losing its grip. In London, Mayor Sadiq Khan warned that the “omnishambles” could severely damage Labour’s prospects in the capital’s May elections, a pointer to how quickly a single misstep can ripple through the party’s electoral machinery.

Opposition parties have escalated the matter by requesting the Speaker refer Starmer to the Privileges Committee, alleging he misled Parliament when he insisted “due process” had been followed in Mandelson’s vetting. That claim is set to face scrutiny on another front: Cat Little, the senior civil servant who oversaw the vetting process, is scheduled to appear before the Foreign Affairs Committee. Her testimony, analysts in London note, will either confirm that proper procedures were circumvented or provide the prime minister with a narrow escape. Either way, the episode has already inflicted lasting damage on the government’s relationship with a civil service that values process as a guarantor of impartiality.

Looking ahead, the prime minister’s attempts to dismiss allegations of a cabinet split as politically motivated ring hollow when set against the scale of unease within his own ranks. The challenge now is twofold: rebuilding trust with a sceptical parliamentary party and reassuring the wider electorate that this government can manage its own affairs. With local elections looming in May and the Conservative opposition scenting weakness, the Mandelson affair has become a defining moment. How Starmer navigates it will determine whether his premiership is remembered for early competence or chronic drift.