British Prime Minister Theresa May looked set to postpone Parliament’s vote on her European Union divorce deal Monday to avoid a shattering defeat, throwing Brexit plans into chaos just weeks after Britain and the bloc finally reached an agreement.

The House of Commons Speaker’s office said May would make a previously unscheduled statement to lawmakers about Brexit 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.

The Press Association news agency and other British media outlets said May had decided to postpone the vote scheduled for Tuesday.

May’s office insisted Monday morning that the vote would definitely be held.

All signs have pointed to a big defeat for the prime minister in Tuesday’s vote — a result that could sink May’s deal, her leadership, or both.

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.

The pound sank amid the political chaos, hitting an 18-month low against the U.S. dollar of $1.2660.

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 upon last month. Britain is scheduled to leave the bloc on March 29.

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 The measure would keep Britain under EU customs rules, and is supposed to last until superseded by permanent new trade arrangements.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. She spoke over the weekend to European Council President Donald Tusk — who will chair an EU summit in Brussels on Thursday — and to 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,” said British Environment Secretary Michael Gove.

But EU leaders insist the Brexit withdrawal agreement can’t be changed.

“The deal is the deal,” Irish Foreign Minister Simon Coveney said Monday. “It’s taken two years to put together. It’s a fair deal for both sides.”

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 British 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 the bloc of 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. But a group of Scottish legislators had asked the ECJ to rule on whether the U.K. could 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.”

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

Scotland’s Constitutional Relations Secretary Michael Russell described Monday’s 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.

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.

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