British MPs on Tuesday begin five days of debate on Prime Minister Theresa May's Brexit deal, ahead of a vote that will determine the future of Britain and her leadership.
May agreed the terms of Britain's withdrawal with the European Union last month, but the text faces opposition on all sides of the House of Commons, and risks being rejected in the vote on December 11.
The Conservative leader will open the debate insisting once again that her deal is the only option for a smooth Brexit next March.
"This is the deal that delivers for the British people," May will tell MPs, according to extracts from her speech released by Downing Street.
"The British people want us to get on with a deal that honours the referendum and allows us to come together again as a country, whichever way we voted," she will say.
She has previously warned that rejecting the deal could see Britain leave the EU with no agreement at all -- something economists warn risks a major recession.
May has also raised the prospect of a change of government that sees Brexit reversed.
The left-wing Labour party, which rejects the deal along with all the other opposition parties and has raised the possibility of a second referendum on Brexit, says it would trigger a confidence vote to bring down her government if May loses.
May, who has been constantly challenged by hardline eurosceptics in her own Conservative party, would also likely face a leadership challenge.
- No deal would be better -
The 2016 vote, in which 52 percent of Britons chose to leave the EU, was deeply divisive and there remain strong feelings on both sides.
Protesters from the different camps gathered outside parliament on Monday, some waving EU flags and others holding up placards insisting that "Leave Means Leave".
MPs are just as divided. Although a large majority voted to start the Brexit process, they cannot agree on how it should end.
Hardline Conservative Brexiteers say May's compromise deal does not represent enough of a break with Brussels.
The Democratic Unionist Party (DUP), the Northern Irish party propping up May's government, also objects to the deal's special provisions for the province.
"It's the bad deal which the prime minister said she would never accept and we would prefer no deal rather than this arrangement," said DUP lawmaker Sammy Wilson.
In a heated parliamentary debate on Monday, Attorney General Geoffrey Cox admitted that the agreement had "unattractive" and "unsatisfactory" elements but said it guaranteed a "peaceful and orderly" Brexit.
May's chief Europe adviser Olly Robbins also on Monday said the Irish border provisions in the deal were "a slightly uncomfortable necessity for both sides".
Many of May's critics want her to go back and renegotiate -- some suggest she could do so immediately. Two days after the Brexit vote, she is due in Brussels for an EU summit.
Growing numbers of pro-European MPs, meanwhile, are pressing for a second referendum. On Monday they delivered petitions to Downing Street signed by one million people.
- Parliament in gridlock -
"It is the only thing you can really do if parliament is in gridlock," former Conservative minister Justine Greening told AFP.
"The problem with the first referendum, if you look back on it, is that nobody knew what leave meant," she added.
The EU Withdrawal Agreement covers Britain's financial settlement, estimated at £39 billion, the rights of EU expatriates and plans for a post-Brexit transition lasting to December 2020.
The transition is intended to give both sides time to strike a new trade and security relationship, as set out in an accompanying political declaration.
If this relationship is not settled by then, the withdrawal agreement provides a "backstop" arrangement that would keep Britain in an EU customs union, with Northern Ireland also following EU rules on regulation of goods.
May insists this is necessary to avoid border checks in Ireland, amid fears of any risk to the fragile peace on the island.
But opponents say this risks tying Britain to the EU for years to come, and with no say in the bloc's rules, leaving it a "vassal state".