British Prime Minister Theresa May on Monday told MPs that the deal she finalised with the European Union (EU) over the weekend is the best one that honours the June 2016 referendum in favour of Brexit.
With a statement to update the House of Commons on the European Council summit in Brussels on Sunday, where the so-called divorce pact with the EU was signed off by the remaining 27 member-states, May began her campaign to try and get the withdrawal agreement through the UK Parliament when it comes up for a vote in the coming weeks.
"I can say to the House with absolute certainty that there is not a better deal available our duty, as a Parliament over these coming weeks - is to examine this deal in detail, to debate it respectfully, to listen to our constituents and decide what is in our national interest," she said.
"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. This is that deal. A deal that delivers for the British people," she added.
MPs from across party lines carried on their attack on the controversial agreement, which is opposed by the Opposition parties as well as many of May's own Conservative Party MPs.
Northern Ireland's Democratic Unionist Party (DUP) has said it will review its parliamentary pact with the Conservatives that props up the May-led government's wafer-thin majority if the deal ends up being approved by MPs.
Opposition Labour Party leader Jeremy Corbyn has said his party will oppose the deal, calling it "the worst of all worlds".
Downing Street has said in the "unlikely event" that Parliament could not agree on the terms of withdrawal, "all necessary action" would be taken to prepare the UK to leave without an agreement.
May's campaign to get her deal through Parliament, which began with an appeal to the public in a "letter to the nation" at the weekend, will also include her briefing Labour MPs on the deal. According to some reports, she wants to challenge Corbyn to an open televised debate to try and show him up over his lack of Brexit alternatives.
Opponents of the deal on either side of the argument say it fails to deliver on what people voted for in the 2016 referendum or what the public were promised during the campaign and afterwards.
Brexiteers argue that rather than taking back control, the UK is giving the EU too much of a say in key areas, including a controversial "backstop" customs arrangement, designed to avoid the need for physical checks of people and goods at the border on the island of Ireland.
Many anti-Brexiteers argue the deal is inferior to remaining in the EU because it will not guarantee frictionless trade, while the UK will no longer have a say in setting rules and regulations it will have to abide by.
As a result, there are also calls for a second "people's vote" so that the public can now make a more informed decision on what Brexit would really mean.
May faces a crucial few days as she builds up consensus around the withdrawal agreement before it comes up for a Commons vote, expected around December 12.
Some members of her Cabinet are reportedly canvassing support for Plan B scenarios, should she fail to win parliamentary backing for her deal.
Britain is scheduled to leave the EU on March 29 next year under the Article 50 process set in motion after the 2016 referendum. Although the departure date is set down in law, Labour's Shadow Brexit secretary Keir Starmer said Parliament must find a way to stop Britain crashing out of the EU without any deal.