U.K. Prime Minister Theresa May is locked in a power struggle with the British Parliament that looks set to determine the final shape of Brexit.

May lost three key votes on a day of drama in the House of Commons on Tuesday, highlighting the weakness of her position as she tries to ratify the deal she’s struck with the European Union.

The result is that Parliament now has the potential to decide on Britain’s "plan B" if -- as expected -- it rejects May’s divorce agreement with the EU in the biggest vote of all next week.

That’s not what the premier wanted. It raises the possibility that members of Parliament could seek to pursue a softer withdrawal -- including potentially staying in the bloc’s single market -- or even attempt to stop Brexit entirely. One option that could gather momentum over the weeks ahead is for a second referendum to allow the public to overturn the decision of the first.

“No longer must the will of Parliament -- reflecting the will of the people -- be diminished,” Tory lawmaker Dominic Grieve said after engineering one of May’s defeats Tuesday. “Parliament must now take back control and then give the final decision back to the public because, in the end, only the people can sort this out.”

Long Odds

On Dec. 11, Parliament will vote finally on whether to accept or reject the 585-page withdrawal agreement that May and the EU reached in November. Few officials in May’s government believe they have much chance of winning, with some Tories predicting a heavy defeat.

If they’re right, the U.K. will be on course to crash out of the EU with no deal, an outcome which the Bank of England and the Treasury warned last week would cause immediate and severe damage to the British economy. According the BOE analysis, house prices would be hit by 30 per cent and the pound would fall by as much as 25 per cent after a no-deal Brexit.

The signs are not good for May’s plan. Labour leader Jeremy Corbyn said the official opposition, which he leads, will oppose her deal next week. Critics from all sides of the House lined up to raise objections to the deal.

Key Votes Lost

Even Northern Ireland’s Democratic Unionist Party, which has a formal role propping up May’s minority Tory government, isn’t backing her.

On a day of fast moving developments on Brexit:

  • An advisory opinion from the EU’s top court indicated that the U.K. can unilaterally decide to reverse Brexit.
  • May lost two House of Commons votes forcing her to publish secret government legal advice on her Brexit deal. After being found in contempt of Parliament -- an unprecedented charge against a government -- May promised she would release the legal file Wednesday. The pound fell as much as 0.5 percent against the dollar.
  • The premier then lost a third big vote that could prove even more significant: it gives Parliament the power to shape the final Brexit settlement if, as expected, May fails to get her deal approved in the Commons in the Dec. 11 vote. The pound pared earlier losses.

Speaking shortly after the defeats, May put on a brave face, and appealed to her colleagues to back her “compromise” plan or risk betraying voters who chose to leave the EU in the referendum of 2016.

Central Figure

“I do not say that this deal is perfect -- it was never going to be,” May told the Commons. “We should not let the search for the perfect Brexit prevent a good Brexit that delivers for the British people.”

The government’s frustration focused on the central figure of Commons Speaker John Bercow. He made the ruling to allow Tuesday’s damaging votes to take place.

According to people familiar with the matter, May’s Cabinet ministers expressed their private anger at Bercow’s handling of Brexit during a meeting earlier Tuesday, with some of those present voicing harsh words about the Speaker. Bercow’s office didn’t immediately respond to a request for comment.

Thanks to May’s defeats Tuesday, it would be the Speaker again who would decide how Parliament can shape the plan B if the premier fails to get her overall Brexit deal through the Commons next week.