Embattled British Prime Minister Boris Johnson simply does not have the numbers he needs to survive.
That's according to London-based correspondent Vincent McAviney, who was speaking as Mr Johnson vowed to stay in power.
This is despite a Cabinet revolt, with more than 40 of his own MPs quitting their government roles and at least one senior Conservative Party member saying they'd be willing to run for the party leadership.
While Brandon Lewis resigned as the UK's Northern Ireland Secretary on Thursday morning.
In a tweet, he said: "A decent and responsible government relies on honesty, integrity and mutual respect.
"It is a matter of profound personal regret that I must leave government as I no longer believe those values are being upheld."
Mr Lewis had been Northern Ireland Secretary since 2020.
A decent and responsible Government relies on honesty, integrity and mutual respect - it is a matter of profound personal regret that I must leave Government as I no longer believe those values are being upheld.
I have submitted my letter of resignation to the Prime Minister. pic.twitter.com/EG6u52BdDc— Brandon Lewis (@BrandonLewis) July 7, 2022
Mr Johnson also sacked Minister Michael Gove late on Wednesday after it was understood he, along with other members of Mr Johnson's top team, told him he should stand down.
And England's Attorney-General Suella Braverman said: "I do think the time has come for the prime minister to step down."
Asked if she had ever thought about standing for prime minister, she told told ITV's Robert Peston: "Yes, I will."
Vincent McAviney told Breakfast Briefing Mr Johnson cannot survive.
"This does seem now completely untenable for Boris Johnson.
"We know - for instance - that Priti Patel, the home secretary, Grant Shapps, the transport secretary, Nadhim Zahawi, the new chancellor, among others in the Cabinet told the prime minister last night he had to go.
"And yet they are still in Cabinet: they either have to resign immediately this morning, or Boris Johnson is going to have to fire them all.
"He simply does not have the numbers to replace those he has lost - he has lost over 40 members of his government now.
"It really is untenable for him to survive, he does not have the numbers he needs to replace those that he's lost.
"And he does not have the calibre of candidates needed to take those top jobs".
While he believes more resignations are coming.
"I think this morning there will be more resignations.
"You cannot, under the British system of collective responsibility, have the secretaries of state in some of the biggest jobs tell the prime minister to go, make it known that they've told the prime minister to go and have them staying in position."
