British Prime Minister Theresa May will have a final roll of the Brexit dice today after securing a 'fudge' on the Irish backstop.
After a day of frantic activity in Dublin, London and Strasbourg, the UK government boasted of achieving "legally binding" changes that "strengthen and improve" the Withdrawal Agreement.
The backstop which ensures no return to a hard Border on the island of Ireland remains unchanged - but there is a vision of an "alternative arrangement" being found by December 2020.
As revealed by the Irish Independent last week, Mrs May and European Commission President Jean-Claude Juncker negotiated a 'package' consisting of three elements.
Brexiteers said they were "keeping an open mind" about the revised deal ahead of a crucial vote today.
Mrs May returns to the UK to win over her detractors with a warning that the EU will not move further and, if the deal does not pass muster, Brexit may not happen at all.
The package includes:
The legally binding statement will set out that the backstop is intended to be temporary.
It commits the EU to using "its best endeavours to negotiate and conclude expeditiously a subsequent agreement that would replace the backstop". A date of December 31, 2020 is prescribed.
Sources in the Irish Government told this newspaper last night that they "can live" with the additions to the original agreement if it helps Mrs May get it passed by the House of Commons.
The 'unilateral' statement prepared by the UK was the focus of most attention in Dublin last night. It sets out the UK government's official interpretation of the backstop - but it will not be signed by the EU side.
Mr Juncker was in contact with Taoiseach Leo Varadkar last night to get his blessing for the document.
A senior source in Dublin said: "Any country can say here's 'what we think'. But they can't needle us. A unilateral statement is fine but it can't say that either side can leave the backstop unilaterally."
Mrs May told a press conference in Strasbourg that the avoidance of a hard Border in Ireland was "absolutely right" but if the backstop ever came into force, "it cannot become a permanent arrangement".
Asked about Britain walking away from the backstop, she replied that the backstop was seen by all sides as an "insurance policy" with the intention it would never be used.
"We've secured in this a very clear timetable that allows the backstop to be replaced by alternative arrangements," she added, in reference to the December 2020 target date.
The UK says that while it could ultimately 'dis-apply' the backstop if it believed it was being used in bad faith it will uphold its obligations under the Good Friday Agreement "under all circumstances and to avoid a hard border on the island of Ireland".
At the same press conference, Mr Juncker stressed that "we want to preserve peace on the island of Ireland" and that the Taoiseach would be prepared to back the new approach.
But in pointed remarks, he warned Britain: "In politics sometimes you get a second chance, it's what you do with this second chance that counts, because there will be no third chance."
He later added: "There will be no new negotiations. It is this."
Mrs May's chances of success in selling this deal now rest with Geoffrey Cox, the UK attorney general, who will today issue fresh legal advice on whether the UK could be trapped forever in the backstop if it came into force as a result of failed trade talks.
Mr Cox had previously said the backstop could "endure indefinitely". But if he changes his mind it may persuade significant numbers of Brexiteers to back the deal, which was defeated by a record margin when it was first put to the vote in January.
Mr Cox, who did not travel to Strasbourg, will need to be convinced that the revisions amount to a legally binding assurance that the backstop is finite in order to change his legal opinion.
The position of Northern Ireland's DUP, which props up Mrs May's government, will also be central to her chances of getting the vote across the line.
DUP leader Arlene Foster is understood to be meeting with senior Conservative Party MPs to discuss the situation.
The DUP's deputy leader Nigel Dodds said everything will need to be taken together and analysed carefully.
Sources in Dublin insisted the package being provided to the UK "does not remove the backstop".
The Cabinet met this morning to receive a final update on Brexit before ministers jet off on their traditional St Patrick's Day trips.
A decision had been taken for Mr Varadkar to fly to Washington yesterday so that he would be on the ground to watch the House of Commons vote. His official programme in the United States doesn't actually begin until Wednesday.
However, while some of his officials made it as far as Dublin Airport, Mr Varadkar decided to stay put shortly before he was due to leave Government Buildings.
Sources said he still fully intends to meet US President Donald Trump in the White House on Thursday, but his travel plans are "fluid".
Tánaiste Simon Coveney has already curtailed his planned visits to Paris, Brussels, The Hague and Berlin.
The Cabinet was called to an emergency session at short notice yesterday evening, leaving a number of ministers scrambling to get back into the city centre.
Ministers have been told to be "extremely cautious" with their public commentary, amid fears that a triumphalist tone from Dublin would immediately derail any progress Mrs May hopes to make within her party.
After discussing the situation in broad terms, the Cabinet broke up to allow the Taoiseach to take a phonecall from Mr Juncker.
Talks between the EU and UK collapsed over the weekend after Mrs May's cabinet rejected the original outline of what is now on the table.
Geoffrey Cox believed it did not go far enough to convince him that the backstop would not "endure indefinitely".
And Labour leader Jeremy Corbyn said parliament must reject the deal today, adding: "The prime minister's negotiations have failed.
"This evening's agreement with the European Commission does not contain anything approaching the changes Theresa May promised Parliament, and whipped her MPs to vote for."
The Irish Government will watch eagerly in the hope that Mrs May can gain support for the deal in today's vote.
However, a number of ministers privately told the Irish Independent that the best outcome at this stage would be a delay.
If Mrs May's deal is defeated again, she has promised two more votes this week: one to rule out leaving the EU without a deal and another which would give her permission to seek a delay of Article 50.
Ireland has repeatedly said it would not block a postponement of Brexit beyond March 29 - but Mr Varadkar was nuanced when speaking to reporters earlier yesterday. He warned that the EU will not allow a delay if it merely creates for a "rolling cliff-edge".
The UK Government has secured "legally-binding" changes to the Brexit deal after Theresa May made a last-minute dash to Strasbourg for talks on the eve of a crucial vote in the House of Commons.