Two days ahead of a vote in parliament that she's expected to lose, British Prime Minister Theresa May warned lawmakers that if they don't back her plan to ditch the European Union the country will face a catastrophe.

Lawmakers in the U.K. are set to vote Tuesday on May's Brexit plan after she shelved plans for a December vote when it became clear she would lose that vote.

Although she still may not get enough support, May wrote in the Sunday Express that members of parliament must not let down the majority of Britons who voted to leave the European Union.

A group of British lawmakers, including some former Tory ministers, are working on a way to allow non-government members to take control of the timetable and bring legislation forward that would make it illegal to leave the EU without a deal, if May loses the vote, according to the Sunday Times.

Downing Street has reportedly said it is "extremely concerned" about the supposed plot, which it says could potentially overturn centuries of Parliamentary precedent.

A group of ordinary Britons -- from a wide range of professions -- told The Guardian that they were being abandoned, ignored or having their rights taken away under the impending Brexit.

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Meanwhile, Brexit Secretary Stephen Barclay told the BBC's Andrew Marr show: "There are lots of different plans being put forward by Members of Parliament that don't respect the result (of the referendum) or risk no deal."

However, when the BBC asked what happens if the deal is defeated, Barclay said he suspected the Commons would support something "along the lines of this deal" but did not speculate on whether the government had a Brexit "plan B" lined up.

“Doing so would be a catastrophic and unforgivable breach of trust in our democracy,” May wrote in the Sunday Express. “So my message to parliament this weekend is simple: it is time to forget the games and do what is right for our country.”

One of May's opponents in the Labour Party said he would table a vote of no confidence in the government if she loses.

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Corbyn said Labour would vote against May's deal, and if she lost would start moves to trigger a general election.

He told the BBC: "We will table a motion of no confidence in the government at a time of our choosing, but it's going to be soon, don't worry about it."

The Labour leader has said his party does not have the votes in parliament to win a confidence vote on its own and has appealed to other parties to support it.

Corbyn also said that a no-deal exit from the EU on March 29 would be "catastrophic for trade."