British Prime Minister Theresa May will fight any attempt to unseat her through a vote of no confidence by Conservative MPs, Downing Street has said.
The defiant message came after Mrs May's administration was thrown into turmoil by the sensational resignations in quick succession of Brexit Secretary David Davis and Foreign Secretary Boris Johnson.
The departure of the two Cabinet "big beasts" came just two days after Mrs May secured senior ministers' agreement at Chequers for a Brexit plan about which both men had expressed reservations.
Mr Johnson's exit was announced by Downing Street moments before Mrs May faced the House of Commons to set out details of her plans.
Mrs May was greeted by loud cheers from Tory MPs and shouts of "resign" from the opposition benches as she arrived to deliver a statement in which she said her proposals would deliver "a Brexit that is in our national interest... the right Brexit deal for Britain".
The prime minister told MPs she wanted to recognise the work of the former Brexit secretary on steering through some of the "most important legislation for generations" and the "passion" that the outgoing foreign secretary had shown in promoting a "global Britain to the world".
But she said: "We do not agree about the best way of delivering our shared commitment to honour the result of the referendum."
Conservative MP Andrea Jenkyns said she believed that Mrs May's time as prime minister was "over", telling BBC Radio 4's Today programme that she wanted a leader who would "provide true leadership and a positive post-Brexit vision for our country".
Senior backbencher Bernard Jenkin said there had been a "massive haemorrhage of trust" in Mrs May.
Asked if Brexiteers needed to put the prime minister’s future to a vote of the Conservative Party, he replied "it may well come to that".
However, there was loud applause as Mrs May left the 1922 Committee gathering in Westminster this evening.
Leaving the meeting, prominent Brexiteer Jacob Rees-Mogg, said he did not think there would be a confidence vote over Mrs May.
Some 48 Tory MPs - 15% of the party's 316-strong representation in the Commons - must write to the chairman of the backbench 1922 Committee, Graham Brady, to trigger a no-confidence vote.
Asked whether Mrs May would fight a no-confidence vote if one was called, a senior Number 10 source said simply: "Yes."
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Mr Davis was first to go, announcing his exit just before midnight on Sunday.
But there was growing speculation about Mr Johnson's plans after he failed to attend a meeting of the Government's Cobra emergencies committee, as well as a summit of Western Balkan nations being held in London.
At 3pm this afternoon, a statement was issued by Downing Street to say: "This afternoon, the Prime Minister accepted the resignation of Boris Johnson as Foreign Secretary. His replacement will be announced shortly. The Prime Minister thanks Boris for his work."
Staunch Brexiteer Dominic Raab was named as Mr Davis's replacement as Secretary of State for Leaving the EU, and a new foreign secretary was expected to be in place by the end of the day.
There is added pressure for a swift appointment because the foreign secretary is due to join Mrs May at the Nato summit in Brussels on Wednesday and take part in the events of US President Donald Trump's visit to the UK, which begins on Thursday.
Mr Johnson was the figurehead of the Leave campaign in the 2016 referendum, but dramatically pulled away from an expected leadership bid after losing the support of fellow minister Michael Gove.
Mrs May surprised many by appointing him to the Foreign Office, a position he has frequently used to forge a distinctive position on Brexit.
He was widely reported to have told the Chequers meeting on Friday that putting a positive gloss on Mrs May's Brexit package would be like "polishing a turd", though he later joined other ministers in signing up to the package.
There was no immediate statement from Mr Johnson to explain his decision to quit, which was seized upon by opposition politicians as a sign of increasing turmoil within Mrs May's administration.
Labour deputy leader Tom Watson said: "Theresa May's Government is in meltdown. This is complete and utter chaos.
"The country is at a standstill with a divided and shambolic Government. The prime minister can't deliver Brexit and has zero authority left."
The leader of the Scottish Conservatives Ruth Davidson said Mrs May was "correct to accept the Foreign Secretary's resignation".