The British Parliament is to begin on Tuesday a five-day debate on the Brexit deal between the EU and the UK before voting on it on December 11.

The vote and the debate leading up to it are going to determine whether Britain leaves the European Union on March 29, 2019, with or without the embattled Brexit deal advocated by Prime Minister Theresa May.

If May loses the vote, she would still be able to call for a second one but a defeat on December 11 would increase substantially the chance that Britain may depart from the EU without a deal, while putting enormous pressure on the Prime Minister to resign, Reuters reports.

A defeat of the EU – UK deal in the British Parliament would also boost the chances for a second referendum on Brexit, and the possibility that Brexit might not even materialize at all.

Regardless May’s efforts, the deal with the EU that she has championed has galvanized severe opposition from both eurosceptics and EU supporters.

Both are indignant that the deal based on her Chequers Plan would make the UK a “taker” of EU rules.

But the deal, sealed in Brussels last month, has united critics at both ends of the political spectrum: eurosceptics say it will make Britain a vassal state while EU supporters – expressing the same idea though with different language – say the country will become a rule taker.

Not just the opposition parties in the British Parliament but also the Northern Irish Democratic Unionist Party, which is May’s coalition partner with its 10 MPs, have made it clear they would not back the Brexit deal.

“The British people want us to get on with a deal that honors the referendum and allows us to come together again as a country, whichever way we voted,” May is going tell lawmakers on Tuesday, according to excerpts of her speech.

“This is the deal that delivers for the British people,” she is going to press ahead with the vote regardless of the known opposition.

“This deal … is the best way I firmly believe of ensuring that we leave the European Union on March 29,” UK Attorney General Geoffrey Cox told the British Parliament on Monday.

“This is the deal that will ensure that happening in an orderly way with legal certainty,” he added.

“This is not Brexit,” stated in turn on Monday Theresa May’s former Brexit Minister David Davis, who quit in July precisely over opposition to her Chequers Plan.

The Prime Minister insists that her deal with its stipulated close economic ties to the EU would achieve both the end of free movement of people and allow the UK to trade unhindered with the rest of the world.

The upcoming five-day debate will see the opposition try to change the deal, or delay or cancel Brexit altogether.

The opposition Labor Party has proposed an amendment requiring that the UK would be unable to leave the EU without an exit deal, and that it must consider all relevant alternatives.

(Banner image: Theresa May on Twitter)