- Video report by ITV News Political Editor Robert Peston
Theresa May has warned ministers if they vote down her Brexit deal to not "imagine another deal is going to miraculously appear".
The stark message came as the Prime Minister kicked off the first of five days of debate before a historic vote on her Brexit deal takes place on December 11.
But, she endured yet another troubling day as her government lost three votes in the space of an hour.
Mrs May reiterated a position she has held throughout negotiations: “The alternative is uncertainty and risk - the risk Brexit could be stopped, the risk we could crash out with no deal.”
She said it would not be in the “national interest” to block the Withdrawal Agreement, adding: “The only certainty would be uncertainty.”
MPs' decisions over the next week would “set the course our country takes for decades to come”, she added.
Mrs May told them: “I promise you today this is the very best deal for the British people, I ask you to back it in the best interests of our constituents and our country.
“And with my whole heart I commend this motion to the House.”
In a speech repeatedly interrupted by MPs attacking her deal, the Prime Minister pledged to give Parliament and the devolved administrations a “greater and more formal role” in forthcoming negotiations with the EU over trade - but declined to say whether MPs would get a vote on that deal.
Labour leader Jeremy Corbyn said Mrs May had achieved something “extraordinary” with her Brexit deal: “Across this House it has achieved something - it has united both Conservative Remainers and Conservative Leavers and members of every opposition party in an extraordinary coalition against the deal.
“Following the 2017 election, the Prime Minister could have attempted to build a consensus, recognising the new arithmetic of Parliament, and sought a deal that brought people together.
”Instead, just like her predecessor - who called a referendum without preparing for the eventuality of a Leave vote - the Prime Minister has seen these negotiations only as an exercise in the internal management of the Conservative Party.“
Earlier, it was announced the BBC would be pulling out of hosting a debate between the two leaders.
Mr Corbyn reaffirmed his stance during the debate and said: ”I am quite happy to debate the Prime Minister.
“I notice she was not very keen to debate during the general election but we understand that.”
The debate saw infighting between Conservative ministers with Boris Johnson sparking disagreement on the benches.
“I must regretfully say to the Prime Minister, I really can't believe there is a single member of this House who sincerely believes this deal we have before us is a good deal”, he said.
One Tory MP was heard saying ”actually, there are a lot“ before Tory former minister Ed Vaizey leapt to his feet to show his support.
Mr Johnson went on: ”There's one - I said sincerely.“
Raising a point of order, Mr Vaizey said: ”I sincerely believe it. I've got no stake in this Government any more but I still think it's the right thing to do.“
Mr Johnson later said: ”The Government's heart has not appeared to be in this deal and I think listening to those who are sent out to defend it and to explain it, they know it is a democratic disaster.“
”It has brought us together - Remainers and Leavers, myself and Tony Blair, the whole Johnson family is united in the belief that this is, I'm afraid, a national humiliation that makes a mockery of Brexit.“