Prime Minister Theresa May has addressed MPs in the House of Commons in a final attempt to gain support for her Brexit deal, despite being dealt blows by the DUP, the attorney general, and the European Research Group (ERG).
Battling a croaky voice and with husband Philip watching from the gallery, she warned MPs that "Brexit could be lost" if her deal is rejected.
It came after the pro-Brexit ERG told its Tory MPs to vote against the prime minister's Brexit deal on Tuesday evening.
Their statement was based on legal advice published by the so-called star chamber of lawyers, who examined the legal basis for Theresa May's declared "legally binding" arrangement on the backstop.
It was the second in a series of major blows for the PM's hopes of convincing enough MPs to support her renegotiated deal in Tuesday evening's meaningful vote.
The attorney general dealt her the first knock by revealing his opinion that the legal risk on the backstop remains unchanged - despite her dash to Strasbourg on Monday night to thrash out new arrangements with the EU.
Attorney General Geoffrey Cox published his damaging legal opinion in the form of a letter to the PM shortly after 11am, contradicting her claims that new assurances were legally binding.
MPs are expected to vote at 7pm, with Environment Secretary Michael Gove saying it is "make your mind up time".
In a final attempt to sway MPs, the prime minister said in the Commons: "The danger for those of us who want to have faith in the British public and deliver on their vote for Brexit, is that if this vote is not passed tonight, if this deal is not passed, then Brexit could be lost."
Responding to Mrs May, Labour leader Jeremy Corbyn said "not a single word" of the Withdrawal Agreement had changed.
He said: "After three months of running down the clock the Prime Minister has, despite very extensive delays, achieved not a single change to the Withdrawal Agreement - not one single word has changed."
Boris Johnson said the PM and attorney general had merely sowed an "apron of fig leaves" to cover the embarrassment of the Brexit deal.
The Uxbridge and South Ruislip MP said: "The result is like Adam and Eve in the Garden of Eden - they have sowed an apron of fig leaves that does nothing to conceal the embarrassment and indignity of the UK."
He dismissed the threat that if the deal was voted down then MPs would take control of the Brexit process, saying that would "upend hundreds of years of constitutional practice" and then leave the UK an "effective colony of the EU".
The former foreign secretary said: "We must take what now seems to be the more difficult route, but in the end the one that preserves our self-respect.
"It is to leave on March 29th as required by law and to become once again an independent country able to make our own choices."
It is thought the attorney general's legal assessment that the UK will not be able to unilaterally leave the backstop will influence a number of MPs to vote against the PM's deal in Tuesday evening's meaningful vote.
The altered deal - achieved by the PM in talks in Strasbourg late on Monday - also states the intention that both sides will set about finding an alternative to the backstop as soon as possible.
Paul Brand claimed the legal assessment means Mr Cox has "signed and sealed the PM’s fate".
Shadow Brexit secretary Sir Keir Starmer quickly responded to Mr Cox's assessment, saying "the Government's strategy is now in tatters".
At a joint press conference with European Commission president Jean-Claude Juncker, following her meeting in Strasbourg, Mrs May said the three new documents agreed provided the legal assurances critics of her stance had called for.
ITV News Europe Editor James Mates described the press conference as "choreographed drama" and said it was "all for nothing".
He added in a tweet: "Geoffrey Cox legal advice says "the legal risk remains unchanged". And EU insisting they have nothing left to give."
On a day of high drama in Westminster, the Cabinet gave its backing to the package, but as the day went by it appeared less likely the rest of MPs would do the same.
Charles Walker, vice chairman of the 1922 Committee of backbench Tory MPs, warned that defeat in the second "meaningful vote" on the Withdrawal Agreement would lead to a general election.
He told BBC Radio 4's World At One: "If it doesn't go through tonight, as sure as night follows day, there will be a general election within a matter of days or weeks."
Downing Street said Theresa May remained "absolutely focused on winning" the vote on Tuesday night and insisted she was not preparing for a general election.
A source said: "We are not preparing for and we do not want a general election. Our position is unchanged."
Foreign Secretary Jeremy Hunt said he was happy with the changes his boss had gain in the last minute negotiations, saying the new legal changes achieved "everything we wanted".
Speaking on Tuesday morning, he said: "We have a chance now to leave the EU on 29 March or shortly there after and if we grab this opportunity tonight we can do that, if we don’t we increase the risk both of a customs union outcome and possibly no Brexit which I know is something none of my colleagues want."
He added: "This is a very important morning, these are legally significant changes. I hope parliament will see that the prime minister has listened to parliaments concerns about the backstop.
"It really has now achieved everything that we wanted, or everything we hoped we could achieve in very very difficult negotiations."
The Prime Minister said she "passionately believed" her Brexit deal addressed concerns raised by MPs who feared the backstop would keep the UK in a customs arrangement with the EU indefinitely, adding that has now delivered what Parliament asked her to do.
Mrs May had hoped the three new documents agreed with Mr Juncker would give MPs the legally-binding reassurances they require to approve her Withdrawal Agreement and Political Declaration on the future EU/UK relationship.
The Commons motion the Prime Minister wants MPs to back describes the first new document as “the legally binding joint instrument” relating to the Withdrawal Agreement.
The Government states that the document “reduces the risk that the UK could be deliberately held in the Northern Ireland backstop indefinitely and commits the UK and EU to work to replace the backstop with alternative arrangements by December 2020”.
The second new document is branded a “unilateral declaration by the UK” which sets out “the sovereign action the UK would take to provide assurance that the backstop would only be applied temporarily”.
The final document is a supplement to the Political Declaration “setting out commitments by the UK and the EU to expedite the negotiation and bringing into force of their future relationship”.
If the package passes the Commons, leaders of the 27 remaining EU states will be asked to endorse the new documents at a scheduled European Council summit in Brussels on March 21 and 22, before the final step of ratification by the European Parliament.
Mr Juncker said he had spoken to Irish Taoiseach Leo Varadkar, who he said had indicated he was “prepared to back this approach in the interests of an overall deal”.
In a letter to EU Council president Donald Tusk, Mr Juncker left the option of an extension to Article 50, but only by a could of months.
He said: “I would like to stress that the United Kingdom’s withdrawal should be complete before the European elections that will take place between 23-26 May this year.”