British MPs are preparing to vote on whether to back Prime Minister Theresa May's deal for leaving the European Union, and are expected to reject it outright.
The so-called "meaningful vote" will take place later as five days of parliamentary debate on Brexit come to an end.
Mrs May has called for politicians to back her deal or risk "letting the British people down" but with many of her own MPs expected to join opposition parties to vote against the deal, it is widely expected to be defeated.
The prime minister is due to close the last day of debate with a speech before voting starts about 7pm (8am NZT). The first votes will be on three or four backbench amendments that could reshape the deal and then the vote on the withdrawal agreement itself.
Mrs May minister addressed her cabinet on Tuesday morning before heading to the Commons for the start of the debate on her deal - which includes both the withdrawal agreement on the terms on which the UK leaves the EU and a political declaration for the future relationship.
It followed a meeting with her backbenchers on Monday night where she made one last appeal for their support before the vote.
She had also tried to reassure MPs from all sides of the House over the controversial Northern Irish "backstop" - the fallback plan to avoid any return to physical border checks between the country and Ireland - having received new written assurances from the EU that it would be temporary and, if triggered, would last for "the shortest possible period".
But many remain opposed to the deal, with about 100 Conservative MPs and the DUP's 10 MPs expected to join Labour and the other opposition parties in voting it down.
Democratic Unionist Party leader Arlene Foster said the backstop "was something that we could not accept" and said her party's MPs would be voting against the deal.
"It (the backstop) does violence to the union - it separates us from the rest of the United Kingdom in a very very obvious way," she said, calling for Mrs May to "get rid" of the backstop.
'You are not children in the playground'
Attorney General Geoffrey Cox opened the last day of debate, calling on MPs to recognise the "value of compromise" and "opt for order [over] chaos".
In an impassioned speech to the Commons with the prime minister by his side, he said voting for the deal was "the first of two keys that will unlock our future with the European Union", allowing the government to focus on the future relationship.
He said that MPs could not underestimate the complexity of Brexit and that the deal offered an "orderly, predictable and legally certain" way of leaving the bloc, without "thousands" of legal issues arising for citizens and businesses.
"If you found yourself suddenly with the rug pulled from under you, not knowing what your legal obligations would be, you would say to this House, 'What are you playing at? What are you doing?'
"You are not children in the playground, you are legislators, and it is your job. We are playing with people's lives," he said.
Former Brexit secretary Dominic Raab said that Brexiteers like him could back a deal if aspects such as the backstop were dealt with.
But he told the BBC's Today programme the EU had played "a smart game of hard ball" and said it was time for the UK to do the same.
If the deal is rejected by MPs, Mrs May has three sitting days to return to Parliament with a "Plan B".
In another development, a cross-party group of anti-Brexit politicians has published proposed legislation to bring about another referendum to ask the public whether they want to remain in the EU or leave under the prime minister's deal.
Speaking to his own backbenchers on Monday night, Labour leader Jeremy Corbyn again condemned the deal and repeated his call for a general election if it was voted down by Parliament. He also promised Labour would call a no-confidence vote in the government "soon".
The European Commission President Jean-Claude Juncker will be returning to the city later to deal with "Brexit-related business".
But Mrs May has no plans to travel to Brussels the day after the vote, her spokesman said. There has been speculation she would will make an emergency visit on Wednesday if her deal was voted down.
EU chief Brexit negotiator, Michel Barnier, will be holding talks with the European Parliament's Brexit steering group in Strasbourg before a debate on Wednesday morning about the result of the meaningful vote.
- BBC / Reuters