LONDON (AP) — The British government’s Brexit plans were thrown into chaos on Monday, with Prime Minister Theresa May making an emergency statement to lawmakers amid signs she would postpone a Parliamentary vote that will decide the fate of her divorce deal with the European Union.

The House of Commons Speaker’s office said May would make the previously unscheduled statement at about 3:30 p.m. (10:30 a.m. EST). The announcement came as May held talks with her Cabinet about the next steps in the Brexit process.

Lawmakers are due to vote Tuesday on the Brexit deal, and all signs have pointed to a big defeat for the prime minister — a result that could sink May’s deal, her leadership, or both.

May’s office insisted Monday morning that the vote would definitely be held, but the BBC and other outlets reported it would be postponed. An updated House of Commons business statement said there would be a statement on “business of the House” after May’s address, indicating a sudden change to the parliamentary schedule.

May’s Conservative government does not have a majority in the House of Commons, and opposition parties — as well as dozens of Conservative lawmakers — say they will not back the divorce deal that May and EU leaders agreed last month.

Pro-Brexit lawmakers say the deal keeps Britain bound too closely to the EU, while pro-EU politicians say it erects barriers between the U.K. and its biggest trading partner and leaves many details of the future relationship undecided.

The main sticking point is a “backstop” provision that aims to guarantee an open border between EU member Ireland and the U.K.’s Northern Ireland post-Brexit. The measure would keep Britain under EU customs rules, and is supposed to last until superseded by permanent new trade arrangements. Critics say it could leave Britain tied to the EU indefinitely, unable to strike new trade deals around the world.

Postponing the vote could give May more time to seek concessions from the EU — even though both May and the bloc insist that the Brexit withdrawal agreement can’t be changed.

May spoke over the weekend to European Council President Donald Tusk — who will chair an EU summit in Brussels on Thursday — and European leaders including Irish Prime Minister Leo Varadkar, amid signs she was seeking to tweak the deal to win over skeptical lawmakers.

“Of course we can improve this deal, and the prime minister is seeking to improve this deal,” Gove said.

But, he warned, “by reopening it, there is a risk that we may not necessarily get everything that we wish for.”

In another twist in the Brexit tale, the European Union’s top court ruled Monday that Britain can change its mind over Brexit, boosting the hopes of people who want to stay in the EU that the process can be reversed.

The European Court of Justice ruled that when an EU member country has notified its intent to leave, “that member state is free to revoke unilaterally that notification.”

Britain voted in 2016 to leave the 28-nation bloc, and invoked Article 50 of the EU’s Lisbon Treaty in March 2017, triggering a two-year exit process.

Article 50 contains few details, in part because the idea of any country leaving was considered unlikely.

A group of Scottish legislators had asked the ECJ to rule on whether the U.K. can pull out of the withdrawal procedure on its own.

The Luxembourg-based ECJ said that given the absence of any exit provision in Article 50, countries are able to change their mind in line with their own constitutional arrangements and that such a move “reflects a sovereign decision.”

The British government is free to do so as long as no withdrawal agreement has entered force.

An EU member state can also choose to change its mind in the case where no agreement has been reached, as long as the two-year time limit, including any transition period, has not expired.

Scotland’s Constitutional Relations Secretary Michael Russell described the ruling as “hugely important.”

“People in Scotland overwhelmingly voted to remain in the EU,” he said. “This judgment exposes as false the idea that the only choice is between a bad deal negotiated by the U.K. government or the disaster of no deal.”

May has repeatedly said the government will not seek to delay or reverse Brexit.

British Environment Secretary Michael Gove, who helped drive the Brexit campaign, said the court ruling would have no real impact.

“We don’t want to stay in the EU … so this case is very well but it doesn’t alter the referendum vote or the clear intention of the government that we leave on March 29,” Gove told the BBC.

Cook reported from Brussels.