Brexit Secretary Dominic Raab has told BBC News he quit the cabinet over “fatal flaws” in the UK’s draft Brexit agreement with the EU.
And he said the UK should be ready to risk a no-deal Brexit in the face of EU “blackmail”.
Work and Pensions Secretary Esther McVey and junior Brexit minister Suella Braverman have also quit.
PM Theresa May took largely hostile questions from MPs for nearly three hours over the agreement.
Theresa May could face confidence vote
Leading backbench Brexiteer Jacob Rees-Mogg has submitted a letter of no confidence in her to Sir Graham Brady, chairman of the Tories’ backbench 1922 Committee. He told reporters that the negotiations had “given way on all the key points” adding: “The deal risks Brexit because it is not a proper Brexit.”
He denied being involved in a coup against the PM, saying he was “working through the procedures of the Conservative Party” which was “entirely constitutional”.
Mr Rees-Mogg said he did not have any leadership ambitions of his own but listed Brexiteers Boris Johnson, David Davis, Dominic Raab, Esther McVey and Penny Mordaunt as among those who would be “very capable of leading a proper Brexit”.
A vote will be triggered if 48 Tory MPs write letters to Sir Graham. It is understood 48 letters have not yet been received.
Downing Street said Mrs May would fight any no-confidence vote.
Asked by Labour MP Mike Gapes if it was time she “stood aside for someone else who could take this country forward in a united way”, Mrs May replied: “No.”
Chief whip Julian Smith said the prime minister “will not be bullied” into changing course.
And Foreign Office minister Sir Alan Duncan described Mr Rees-Mogg’s comments as “deeply destructive” and warned Conservative MPs: “If this government is undermined further, we could destroy the government, we could significantly damage and even destroy the Conservative Party, all of which would be happening in the middle of an unconcluded set of Brexit negotiations.”
He added: “We have a massive responsibility to exercise our judgement in a climate of what has to be compromise.”
The day after Theresa May announced that she had secured the backing of her cabinet for the withdrawal agreement, she told MPs it was not a final agreement, but brings the UK “close to a Brexit deal”.
She said it would allow the UK to leave the EU “in a smooth and orderly way” on 29 March, but was met with laughter and shouts of “resign”.
Mrs May told MPs the agreement would deliver the Brexit people voted for and allow the UK to take back control of its “money, laws and borders”.
But Labour Leader Jeremy Corbyn said: “This is not the deal the country was promised and Parliament cannot – and I believe will not – accept a false choice between this bad deal and no deal.”