Britain's health minister Wes Streeting announced Thursday that he had resigned, paving the way for him to launch a leadership challenge against embattled Prime Minister Keir Starmer.
In his resignation letter to Starmer, which Streeting posted on X, he said: "It is now clear that you will not lead the Labour Party into the next general election".
He added that he had "lost confidence" in Starmer's leadership, and a debate about what comes next for the ruling party "needs to be broad, and it needs to be the best possible field of candidates".
Streeting, 43, did not say whether he had the required support of 81 Labour MPs — 20% of the party in parliament — to trigger a contest.
Starmer, who led his Labour party to victory in 2024 elections ending 14 years of Conservative rule, is fighting to save his job after disastrous local and regional polls last week.
Four junior ministers have resigned and more than 80 Labour MPs have urged him to quit, but he has vowed to cling on and more than 100 lawmakers from the ruling party have called for him to stay.
Thursday, his former deputy Angela Rayner announced that UK tax authorities had "cleared" her of deliberate wrongdoing in a tax affair, opening the way for her to compete in a potential leadership race.
The 46-year-old insisted she would not be the one to trigger a contest, but told the Guardian newspaper she would play "whatever role I can" to "deliver the change".
Rayner, a left-wing figurehead hugely popular among Labour's grassroots activists, also called on Starmer to "reflect" on his position.
She was forced to step down in September for underpaying a property duty, but said Thursday the UK tax authority HMRC had exonerated her of "the accusation that I deliberately sought to avoid tax".
Rayner quit as deputy PM and housing, communities and local government minister after an investigation found she had breached the ministerial code over the purchase of a flat in southern England. Media reported she had paid off £40,000 ($54,000) in outstanding tax.
Local poll drubbing
Streeting is popular on the right of Labour, but is disliked by MPs on the left who would prefer Rayner or Greater Manchester Mayor Andy Burnham as leader.
Burnham is currently blocked from running as he does not have a seat in the Westminster parliament. His supporters want Starmer to set a detailed timetable for his departure that allows Burnham to stand.
Starmer's spokesman insisted Thursday that the prime minister was going nowhere.
He "is purely focused on governing. He is getting on with the job of doing just that," the spokesman told reporters.
Voters last week punished Starmer over his 22 months in power in local ballots which saw huge gains for the hard-right Reform UK party and the left-wing populist Greens at Labour's expense.
The Labour Party lost control of the devolved Welsh parliament for the first time and failed to make up ground on the pro-independence Scottish National Party (SNP) in the parliament in Edinburgh.
Rayner earlier stopped short of calling for Starmer to resign, but said voters were frustrated with the way the government was being run.
Starmer has vowed to fight any contest and came out fighting on Monday, pledging to do better and prove his doubters "wrong".
He has been backed by several senior cabinet ministers, including Finance Minister Rachel Reeves, who urged colleagues Thursday not to put the economy "at risk" by "plunging the country into chaos" with a leadership challenge.