Theresa May is making a final push to win over MPs ahead of Tuesday’s crucial Commons vote on her Brexit deal.
The prime minister’s withdrawal agreement has already been endorsed by the 27 other EU leaders but now it faces its toughest test in parliament.
Downing Street has maintained the vote will go ahead on Tuesday, despite weekend newspaper reports claiming it would be delayed.
It comes as the European Court of Justice rules that the UK can unilaterally revoke Article 50 and reverse its decision to leave the EU.
Mrs May plans to hold a number of private meetings with backbench MPs on Monday in a last-ditch effort to gain their support.
She says the UK could face another general election – or possibly no Brexit whatsoever – if her deal is rejected.
However, the government is expected to lose the vote as Labour, the Liberal Democrats, the DUP, the SNP and dozens of Conservative MPs say they will not support the deal.
The backstop to prevent a hard border in Ireland is thought to be the main sticking point among Tory MPs who are against the withdrawal agreement.
Mrs May spoke to Irish premier Leo Varadkar on the phone on Sunday evening, as well as European Council president Donald Tusk.
But she must sway her own MPs if she is to pull off a political miracle and get her deal through parliament. Should she lose, her own political future will be at stake.
Mrs May warned Tory would-be rebels the country would be in “uncharted waters” if the deal is rejected.
“It would mean grave uncertainty for the nation with a very real risk of no Brexit or leaving the European Union with no deal,” she told the Mail on Sunday.
“We have a leader of the Opposition who thinks of nothing but attempting to bring about a general election, no matter what the cost to the country.
“As someone who cares passionately about my country and my party, I believe Jeremy Corbyn getting his hands on power is a risk we cannot afford to take.”
Mr Corbyn told ITV News the prime minister’s Brexit deal was “ridiculous” adding: “It’s going to be defeated, I hope, on Tuesday.
“At that point they’ve got to go back, negotiate something that is acceptable, which does protect rights and conditions, which does give us that trade access, or they’ve got to get out of the way, have an election so that it will be a government here that will be serious about those negotiations.”
Former work and pensions secretary Esther McVey said she would give the prospect of standing as leader “serious concern” and suggested that Brexiteers should unite around a single candidate.
Former foreign secretary Boris Johnson pointedly refused to rule out challenging Mrs May, although he insisted it was “nonsense” to suggest he was already lining up members of his Cabinet.
Asked to give an “absolute, categorical promise” that he would not stand against the prime minister, Mr Johnson told the BBC’s Andrew Marr Show: “I will give you an absolute, categorical promise that I will continue to advocate what I think is the most sensible plan.”
Former Brexit secretary Dominic Raab told Sky News’s Sophy Ridge On Sunday “I’ve always said I wouldn’t rule it out” but “it would be very self-indulgent to be engaging in all that speculation when we’ve got such a big issue up for decision on Tuesday”.
Former attorney general Dominic Grieve suggested that the Tory party could split over Brexit.
Labour is considering its options if Mrs May is defeated and would hold talks with other opposition parties about how to proceed.
The party wants a general election but shadow Cabinet Office minister Jon Trickett said Mr Corbyn would be prepared to lead a minority government this week.
Mr Trickett told Sky: “Our preferred option, very, very strongly, is that we refresh the parliament though we are ready to form a minority government should that be necessary – and it could happen on Wednesday morning.”