Boris Johnson is stepping down as prime minister but is expected to remain in place in a caretaker role until a new leader is announced in the autumn.
The prime minister is poised to announce his resignation following an onslaught of resignations in protest over his leadership.
More than 50 MPs have resigned from government or party roles since Tuesday night after it emerged Mr Johnson promoted Tory MP Chris Pincher despite knowledge of misconduct claims against him.
Mr Johnson is expected to remain as prime minister until a successor is appointed, which is likely to be by the time of the Conservative Party conference in October.
The timetable for the Tory leadership contest will be agreed between the 1922 Committee, which runs the parliamentary proceedings to whittle the candidates down to two, and Conservative headquarters.
Mr Johnson would be staying on as caretaker prime minister – someone who temporarily runs the government until a new leader is appointed.
However his critics have suggested he should not be allowed to remain in office until the autumn and that someone else should step into the caretaker role.
George Freeman, who quit as science minister on Thursday morning, said that now Mr Johnson had “finally done the decent thing” he should “hand in the seals of office, apologise to Her Majesty, allow her to appoint a caretaker under whom ministers can serve, so the Conservative Party can choose a new leader properly”.
Scotland’s first minister Nicola Sturgeon also questioned whether it was “sustainable” for him to remain in the role until the autumn.
She tweeted: “There will be a widespread sense of relief that the chaos of the last few days (indeed months) will come to an end, though notion of Boris Johnson staying on as PM until autumn seems far from ideal, and surely not sustainable?
“Boris Johnson was always manifestly unfit to be PM and the Tories should never have elected him leader or sustained him in office for as long as they have.”
One unnamed Conservative source told the Daily Mail former prime minister Theresa May could be brought back for a caretaker role when Mr Johnson steps down.
Another alternative could be deputy prime minister Dominic Raab, who stepped into the role of acting prime minister when Mr Johnson was hospital with Covid-19, and more recently while he recovered from a routine sinus operation.
A No 10 source on Thursday said Mr Johnson spoke to Sir Graham Brady, chairman of the Conservative 1922 Committee, to inform him of his decision to resign.
“The prime minister has spoken to Graham Brady and agreed to stand down in time for a new leader to be in place by the conference in October,” the source said.
The resignation comes after the prime minister haemorrhaged support among his ministers and MPs.
Mr Johnson had sought to defy his critics and carry on in office, despite warnings from Cabinet colleagues that this was not sustainable.
But resignations continued and chancellor Nadhim Zahawi - who was only appointed to the role on Tuesday - went public with his call for the prime minister to quit.
