British Prime Minister Keir Starmer is set to decide the fate of his political future after his rival Andy Burnham's decisive parliamentary by-election victory prompted more ministers in the ruling Labour Party to call for his resignation.

A source said Starmer may reach a decision by Monday, either stepping down or contesting a leadership race against Burnham. The prime minister currently faces one of the lowest approval ratings among British leaders.

Pressure on Starmer intensified following Burnham's landslide win in north-west England, with dozens of MPs and some ministers privately urging him to set a timetable for leaving office to clear the way for Burnham, the former Mayor of Manchester.

A well-placed source said Starmer was spending the weekend reflecting on his position and discussing it with his family, and that an expected conversation with Burnham could clarify matters. The source added: "Keir tends to think things through."

Results from local elections held in May revealed a sharp decline in support for Starmer after the governing party suffered heavy losses. Opinion polls among Labour members indicate that Burnham would win such a contest. If Burnham were to take the leadership, he would become Britain's seventh prime minister in 10 years.

Sky News reported that it had received information indicating that Foreign Secretary Yvette Cooper urged Starmer to stand down during a private conversation earlier in the week. A spokesperson for her had not responded to a request for comment. That call, alongside demands from other ministers and dozens of MPs, reinforced the impression that Starmer's departure is a matter of when, not if.

Starmer said days ago that he would contest any formal Labour leadership challenge. While Starmer's team argues that his landslide general election victory in 2024 gives him a mandate to remain in office until 2029, Business Secretary Peter Kyle said the prime minister is reflecting on the political challenges he faces at this moment.

Kyle added that he had spoken with Starmer and found a man questioning what the country expects of him. He said the conversation showed that Starmer was going through extremely difficult circumstances. Kyle told LBC radio: "I won't deny the political challenges he faces right now, but I also won't say this will be resolved in the coming days."

Burnham's sweeping victory over the populist Reform Party and his win of the Macclesfield parliamentary seat prompted more MPs and ministers to intensify pressure on the prime minister to set a timetable for his exit, in order to avoid a leadership race that could trigger deep divisions.

The team of Burnham, the veteran politician, said he would give Starmer the weekend to reflect on his position, in the hope of reaching a plan for an orderly leadership transition.

No indications had emerged by then that the two men had spoken. Former minister Jess Phillips, a supporter of Health Secretary Wes Streeting — another potential rival to Starmer — told the BBC:

"It seems we have reached the end of the road," adding that it would be better for Starmer to leave with as much dignity as possible.

Adding to the pressure on Starmer, US President Donald Trump posted on Truth Social predicting that Keir Starmer would resign as British prime minister.