LONDON—With just over a month until the U.K. is set to leave the European Union, British Prime Minister Theresa May’s efforts to garner support for a Brexit deal will go down to the wire, as she tries to herd her divided party toward a knife-edge vote that now looks likely to take place in March.
On Tuesday, Mrs. May urged lawmakers to give her more time to negotiate a new version of her Brexit deal. That deal sets out critical terms for the separation of the U.K. from the rest of the EU, necessary to ensure smooth economic ties between Britain and its biggest trading partner after the country leaves the bloc.
The Brexit deal she hammered out with the EU was rejected in the British parliament by more than 200 votes last month. With the U.K. set to leave the EU on March 29. Mrs. May is now asking other EU leaders to revise key portions of the deal, but they have so far refused.
With talks in limbo, Mrs. May hopes that the rising threat of the U.K. leaving the EU at the end of March without a deal—a scenario that all sides agree will bring economic chaos—will cajole her lawmakers and the EU to endorse a slightly revised version of the Brexit agreement.
On Tuesday, Mrs. May rejected the idea that she is wasting time. “I wanted to have this sorted by Christmas,” she told jeering lawmakers. “It is not me that is trying to run down the clock.”
A make-or-break moment could come at the next EU summit scheduled for March 21, just a few days before the U.K.’s scheduled exit from the trading bloc.
At that time, leaders could agree on a fresh deal. That would nonetheless leave just a few days for British lawmakers to ratify any fresh agreement.
Opposition Labour Party leader Jeremy Corbyn derided Mrs. May’s negotiating tactics as simply “more excuses and more delays.”
Meanwhile, British parliamentarians could pressure Mrs. May into requesting an extension of the Brexit negotiations. On Feb. 27, they will vote on a series of amendments to her original Brexit bill. One could include a demand for an extension if a deal isn’t reached by a certain date. The EU member states would then have to agree to grant the extension.
Mrs. May rejects the idea of an extension beyond March 29, in part because lawmakers in her own party who advocate a clean break from the EU fear it opens the door for Brexit to be canceled altogether. However, turning any Brexit deal into British law requires further parliamentary votes and could take weeks.
One possible solution is for Mrs. May to seek votes from the opposition Labour Party for an eventual Brexit divorce deal. The Labour Party said it would back a Brexit deal if it kept the U.K. in a customs union with the EU, essentially keeping close economic ties with the bloc even after Britain leaves.
Such an option risks splintering Mrs. May’s Conservative party, since euroskeptics in the party have fiercely rejected such an idea as betraying the original 2016 referendum to separate from the EU. On Tuesday, Mrs. May tried to entice wavering Labour lawmakers, promising that the U.K. would seek to uphold worker rights after Brexit.
Business leaders meanwhile are lobbying for a deal to be secured soon. “It is in the interests of everyone, arguably everywhere…that a Brexit solution that works for all is found in the weeks ahead,” said Bank of England Gov. Mark Carney.
With U.K. lawmakers having rejected Theresa May’s Brexit deal, WSJ’s Stephen Fidler explores what options remain available to the prime minister before the country is scheduled to leave the EU on March 29.
—Paul Hannon contributed to this article.
Write to Max Colchester at email@example.com