The PM has fired Levelling Up, Housing and Communities Secretary Michael Gove, who earlier called for him to resign
A No 10 source calls Gove a "snake" and insists the PM will "fight on"
It comes after a group of cabinet ministers - Home Secretary Priti Patel among them - visited the PM to tell him to quit
Secretary of State for Wales Simon Hart was also said to be in that delegation and has now become the third cabinet minister to resign
Attorney General Suella Braverman and ex-minister Matt Hancock have also called for Johnson to go, with Braverman saying she would stand for leader
Another group - including Nadine Dorries and Jacob Rees-Mogg - are thought to have been at No 10 to show support for Johnson
At least 44 ministers and aides have quit since yesterday when Sajid Javid and Rishi Sunak said they were resigning
MPs are angry at Johnson's handling of sexual misconduct claims against former deputy chief whip Chris Pincher
Image source, ReutersCulture Secretary Nadine Dorries has arrived at No 10.
Dorries has been backing Boris Johnson, saying the prime minister "consistently gets all the big decisions right".
Nadhim Zahawi - the new chancellor - is part of the group of cabinet ministers currently in No 10, as well as Simon Hart and Grant Shapps. Brandon Lewis is expected to go later.
The BBC understands that Boris Johnson is also back inside No 10 after his appearance at the Liaison Committee.
Image source, PA MediaTransport Secretary Grant Shapps has just walked into No 10.
He's one of the cabinet ministers who are planning to tell the PM it's time to stand down.
The 1922 committee of Tory backbenchers has decided not to change the rules to allow a second confidence vote against Boris Johnson, the BBC has been told.
It will instead hold an election on Monday to choose its new executive.
Any rule changes would be discussed by the new executive.
Last month, Johnson survived a confidence vote by Conservative MPs. Under existing rules, he is immune from another confidence vote for a year since the last one.
Nick Eardley
Political correspondent, BBC News
The BBC has been told that Business Secretary Kwasi Kwarteng is also calling on Boris Johnson to resign, and has said so to the chief whip.
The PM has told the Commons Liaison Committee in the past half hour he is not going to step down.
Ione Wells
Political Correspondent, BBC News
Nadhim Zahawi, who only yesterday accepted the role of chancellor after Rishi Sunak resigned, is among the delegation that is set to tell Boris Johnson to resign, the BBC understands.
Image source, ReutersCabinet minister Anne-Marie Trevelyan has been photographed arriving in Downing Street within the past half hour.
We don't know whether she is among the group of cabinet ministers who are planning to tell the prime ministers that it is time to go.
Leila Nathoo
BBC political correspondent
There's been talk around Westminster about the possibility of an early general election.
To finish the Liaison Committee, Bernard Jenkin tries to pin the prime minister down on whether he will rule out dissolving parliament if he doesn't have the confidence of a majority of his MPs.
Boris Johnson insists he sees no reason to call an election - and says the earliest date he could see one would be two years from now.
With a delegation of cabinet ministers waiting in Downing Street to tell him it's all over - we might well be about to find out what his next move will be.
There've been some slightly surreal moments at the Liaison Committee, where Boris Johnson is being grilled by senior MPs.
Meanwhile the resignations from his government pile up, and, as we've been reporting, other ministers are preparing to meet him to urge him to step down.
Johnson told the committee that he was having a "terrific" week:
Boris Johnson says he is having 'terrific' week
PM offers no comment on ministers set to tell him to go
Chair of the Business Committee Darren Jones puts it to Johnson there are reports that a delegation of ministers are preparing to tell him to leave office.
He says, in the middle of the Liaison Committee session, that a group of cabinet ministers are "in Downing Street including the chief whip, transport secretary and your new chancellor waiting to tell you when you finish here today that it's time for you to go".
Boris Johnson says he will not give a running commentary on things he isn't aware of.
Back to the Liaison Committee now, and Conservative MP William Wragg, who has been critical of Boris Johnson, has paid tribute to the PM for turning up to today's grilling by MPs, saying it must have been difficult because of today's events.
Johnson responds, saying he wouldn't be anywhere else.
Wragg then quizzes him about the process of appointing former deputy chief whip Chris Pincher.
Johnson says "with a bit of hindsight I can see that appointment... was a mistake".
It is the government's handling of the controversy around Pincher that has prompted the wave of resignations we're now seeing.
Chris Mason
Political editor, BBC News
The Transport Secretary Grant Shapps is also part of the delegation.
He is expecting to go to see the prime minister early this evening.
Chris Mason
Political editor, BBC News
I understand the Northern Ireland Secretary Brandon Lewis is one of those cabinet ministers intending to join a delegation of colleagues going to see the prime minister to tell him he must resign.
Ione Wells
Political Correspondent, BBC News
As we've just told you, a group of cabinet ministers are set to tell Boris Johnson it's time to go.
Welsh Secretary Simon Hart is among them. He made it clear to No 10 yesterday that it was "game over" but it shouldn’t have to come by ministerial resignations.
A group of cabinet ministers are about to tell the PM to resign, including the chief whip, the BBC understands.
Prime Minister Boris Johnson was asked during the Liaison Committee, which is still taking place, whether he'll be in post by tomorrow.
His answer was brief: "Of course."
Boris Johnson says 'of course' he will be PM tomorrow
Leila Nathoo
BBC political correspondent
Reality is increasingly intruding on this committee hearing, which Boris Johnson is trying to keep confined to government business.
One Select Committee Chair, Huw Merriman, who's questioning the PM, has put out his statement of no confidence in him from within the room.
And another, Darren Jones, asks him point blank whether Michael Gove told him to resign this afternoon. Boris Johnson says he won't give a running commentary on political events.
This marathon session of the Liaison Committee - where Boris Johnson is facing a sustained grilling from senior MPs - is continuing.
The PM did not deny media reports that Housing Secretary Michael Gove has called for him to step down.
Asked at the committee about whether this happened, Johnson says he won't give a "running commentary" on events.
Image source, ReutersForeign Secretary Liz Truss does not think this is the time to quit, the BBC understands.
Truss, who is often touted as a potential leader of the party, believes that the situation with the war in Ukraine and the protocol legislation, which is currently going through Parliament, means this is not the moment to step down.
Yesterday, the Foreign Secretary appeared to stand behind Johnson, after cabinet colleagues Sunak and Javid quit.
Huw Merriman has been grilling the PM on the Liaison Committee
We've seen a lot of Conservative MPs share their letters of no confidence in the prime minister on Twitter - but the timing of Huw Merriman's stands out.
Merriman's letter was posted on Twitter, external while he was grilling Boris Johnson at the Liaison Committee.
It is not clear if Merriman sent the tweet or if someone else sent it on his behalf.