Health minister Zubir Ahmed resigned in protest at prime minister Keir Starmer's leadership on Tuesday (12), joining a handful of junior ministers who have quit in a similar fashion.
Dozens of his MPs called for Starmer's resignation following heavy losses in local elections last week.
"It is clear to see that whatever the magnitude of individual achievements and progress, they are now being dwarfed and undermined by a lack of values-driven leadership at the centre," he said in a resignation letter posted on X.
"It is clear from recent days, that the public across the UK has now irretrievably lost confidence in you as Prime Minister."
The government has appointed Preet Kaur Gill to replace Dr Ahmed as parliamentary under-secretary in the Department for Health and Social Care.
She has previously served as a shadow minister for primary care between 2023 and 2024.
Streeting may quit
Meanwhile, health secretary Wes Streeting is preparing to resign and could quit as early as Thursday (14), the Times reported on Wednesday (13), adding that he is likely to mount a formal challenge for the party leadership.
Streeting had a brief meeting with prime minister Keir Starmer on Wednesday (13) ahead of the King's Speech, the report said, citing allies of Streeting who said he had made clear he was determined to proceed with the challenge.
The meeting at Downing Street lasted less than 20 minutes, which has been dubbed by British media as a showdown.
Discussions have also taken place about preparing nomination papers for MPs to back a leadership challenge, according to the Times.
Starmer faces revolt
Meanwhile, Starmer is fighting for his political survival following heavy losses in local elections last week.
He promised on Wednesday to press ahead with plans to reform Britain and warned of chaos if he were to be ousted.
Starmer has so far defied calls to quit from around 90 Labour lawmakers who blame him for heavy losses and say he has failed to deliver reforms since coming to power in a landslide 2024 election victory.
While almost a quarter of the prime minister's elected lawmakers have called for him to go and a handful of junior ministers have resigned in protest, potential rivals for his job have yet to trigger a formal leadership challenge.
Parliament ceremony
Starmer will on Wednesday (13) take part in the State Opening of Parliament - a grand ceremony led by King Charles which is used by the government to set out its political priorities and legislative agenda for the year ahead.
"Britain stands at a pivotal moment," Starmer said in a statement. "To press ahead with a plan to build a stronger, fairer country or turn back to the chaos and instability of the past."
He said Britons expected the government to focus on cutting the cost of living, bringing down hospital waiting lists and keeping the country safe in an "increasingly dangerous world".
A package of over 35 bills and draft bills will focus on measures to improve the economy, strengthen national security and "reform the state to support a more active government that is on the side of British people", the government said.
