The MPs will vote tonight on the exit deal Prime Minister Theresa May has thrashed out with the European Union. If they vote the deal down, they will vote Wednesday on whether to leave without a deal.
The future of Britain's exit from the European Union hung in the balance on Tuesday as lawmakers prepared to vote on a divorce deal after Prime Minister Theresa May won last-minute assurances from the European Union.
Scrambling to plot an orderly path out of the Brexit maze just days before the United Kingdom is due to leave, May rushed to Strasbourg on Monday to agree 'legally binding' assurances with European Commission President Jean-Claude Juncker.
British lawmakers, who on January 15 voted 432-202 against her deal, were on Tuesday studying the assurances with lawyers. The government's top lawyer, Geoffrey Cox, is due to give his opinion on Tuesday ahead of the vote due around 1900 GMT.
"We have secured legal changes," May said in a late night news conference in Strasbourg beside Juncker, 17 days before the United Kingdom is due to leave the EU on March 29.
May said the assurances created an arbitration channel for any disputes on the backstop, "entrenches in legally-binding form" existing commitments that it will be temporary and binds the UK and EU to starting work on replacing the backstop with other arrangements by December 2020.
After two-and-a-half years of haggling since the 2016 Brexit referendum, Juncker cautioned this was the last chance for Britain. "It is this deal or Brexit might not happen at all," he said.
Sterling rose 1.5 percent against the dollar and to a near two-year high against the euro.
If lawmakers vote down May's deal, she has promised a vote on Wednesday on whether to leave without a deal and, if they reject that, then a vote on whether to ask for a limited delay to Brexit.
The United Kingdom's labyrinthine crisis over EU membership is approaching its finale with an array of possible outcomes, including a delay, a last-minute deal, a no-deal Brexit, a snap election or even another referendum.
Brexit will pitch the world's fifth largest economy into the unknown and many fear it will divide the West as it grapples with both the unconventional U.S. presidency of Donald Trump and growing assertiveness from Russia and China.
Supporters of Brexit say while the divorce might bring some short-term instability, in the longer term it will allow the United Kingdom to thrive and also enable deeper EU integration without such a powerful reluctant member.
Brexit-supporting lawmakers in May's party had accused her of botching the negotiations with Brussels. Many Brexiteers fear the backstop, aimed at avoiding controls on the border between the British province of Northern Ireland and EU-member Ireland, could trap the United Kingdom in the EU's orbit indefinitely.
May announced three documents - a joint instrument, a joint statement and a unilateral declaration - which she said were aimed at addressing the Irish backstop, the most contentious part of the divorce deal she agreed with the EU in November.
Former Brexit Secretary David Davis welcomed the requirement to make alternative arrangements for the backstop, the date and the international arbitration.
"All those things together, make this just about, just about acceptable to me but it depends very, very heavily on a robust, clear response from (Attorney General Geoffrey) Cox," Davis told Talk Radio. "If Geoffrey Cox is at all equivocal about it then I think it will fall again."
The immediate reaction was cautious from Brexit-supporting lawmakers and from the Northern Irish Democratic Unionist Party (DUP) which props up May's minority government.
"We will be taking appropriate advice, scrutinising the text line by line and forming our own judgement," a DUP spokesman said.
Jacob Rees-Mogg, leader of a faction in May’s Conservative Party demanding a clean break from the EU, also said he was waiting for legal advice. "This has been desperately rushed," he told the BBC. "I think it would be better to have the vote tomorrow when people had more mature consideration."
The motion put forward by the government said the joint instrument "reduces the risk" that the United Kingdom would be trapped in the backstop.
If the backstop comes into force and talks on the future relationship break down, May said the unilateral declaration she announced would make clear there was nothing to stop London from moving to leave the backstop.
Former Attorney General Dominic Grieve, an opponent of Brexit, said the changes to May's deal did not make a material difference.