The prime minister has vowed to fight on, but growing pressure inside the party has fueled expectations that he could soon set out a timetable for leaving Downing Street.

Sir Keir Starmer is facing the most serious threat to his premiership, as signs grow that he may use Monday to announce a plan to stand down after a dramatic shift in mood across the Labour Party.

The prime minister has repeatedly insisted that he will not resign and that he would contest any formal leadership challenge. But the political atmosphere around Downing Street has changed sharply, with senior figures increasingly discussing not whether his leadership can survive, but how an orderly transition might be managed.

Reports suggest Starmer has been weighing his future after days of pressure from Labour MPs, cabinet ministers, advisers, trade union figures and party donors. The immediate trigger has been the growing momentum behind Andy Burnham, whose return to Westminster through the Makerfield byelection has turned speculation about a challenge into a direct threat to Starmer’s authority.

Burnham, the former Greater Manchester mayor, is now widely seen as the leading figure around whom Labour MPs could unite. Some reports suggest he has the backing of a large bloc of MPs, potentially enough to make a leadership contest difficult for Starmer to survive.

The sense of crisis marks a dramatic reversal for a prime minister who entered office after Labour’s landslide general election victory in 2024. Starmer promised stability after years of Conservative turmoil, but his government has since been damaged by weak polling, internal divisions, policy reversals and frustration over the pace of change.

For months, Starmer’s allies argued that his electoral mandate gave him the right to continue. But the argument has become harder to sustain as Labour MPs grow more worried about the party’s direction and its ability to hold off political challengers, including Reform UK. Reuters reported that Starmer could decide as early as Monday whether to resign or fight a leadership battle.

Downing Street has continued to push back against claims that a resignation is inevitable. Business Secretary Peter Kyle said he had no reason to believe reports that the prime minister would resign on Monday, while government sources have insisted Starmer remains focused on the job.

Still, the language from senior Labour figures has shifted. Instead of simply defending the prime minister, some are now emphasizing the need for dignity, stability and the national interest — phrases often used when parties are preparing for a managed handover.

If Starmer does step aside, Labour would face a delicate choice: a full leadership contest or a faster transition behind a consensus candidate. Burnham’s supporters argue that the party needs a new political direction and a leader with stronger public appeal. Others warn that a rushed coronation could deepen divisions and raise questions about democratic legitimacy.

The stakes go beyond Labour’s internal politics. A change of prime minister would again place Britain in a period of uncertainty, with opponents likely to demand a general election and question whether a new leader could govern without a fresh mandate.

For now, Starmer remains in office and has not publicly abandoned his pledge to fight on. But the political pressure surrounding him is intensifying. Monday may determine whether he tries to reassert control — or begins the process of ending his time in No 10.