LONDON — Jeremy Corbyn, the leader of Britain’s Labour Party, agreed at a meeting of opposition lawmakers on Tuesday to shelve his plan for toppling Prime Minister Boris Johnson next week and instead focus on passing a law to head off a no-deal Brexit.
That strategy, favored by more centrist lawmakers, will face considerable hurdles when Parliament reconvenes in September. But the ability of the anti-Brexit contingent in Parliament to agree on any plan at all was a mark of progress for a group that has been rived by disagreements about how to stop Mr. Johnson, who has vowed to pull Britain out of the European Union by Oct. 31, with or without a deal.
Mr. Johnson has sought to use the threat of a no-deal Brexit as leverage in talks with the European Union on modifying the plan for Britain’s withdrawal, and managed to hold the door open to a reworked Brexit deal in talks with European leaders this weekend.
From Mr. Johnson’s perspective, then, any effort to reduce the threat of a no-deal Brexit is counterproductive. His office on Tuesday railed against the opposition’s plan, calling it “utterly perverse that Corbyn and his allies are actively seeking to sabotage the U.K.’s position.”
But the prospect of a new Brexit deal before Oct. 31 remains slim. And for advocates of staying in the European Union, the word on Tuesday that lawmakers opposed to a no-deal Brexit were ready to collaborate, at least for the moment, was a welcome sign.
“A group of politicians who may personally loathe each other got together and decided that constructive engagement was more useful than enabling medicine shortages,” wrote Jonathan Lis, the deputy director of British Influence, a research institute, alluding to the predicted fallout of a no-deal Brexit. “If they carry on like this, they may just be able to save people’s livelihoods and defeat Boris Johnson.”
If the plan agreed to on Tuesday succeeds in tying Mr. Johnson’s hands, it could give him all the reason he needs to call an early general election. That would give him a chance to expand the Conservatives’ paper-thin working majority and strengthen his negotiating position in Brussels.
But in another twist in the yearslong Brexit drama, some analysts wonder whether Mr. Corbyn remains as enthusiastic about an early election himself, given his feeble poll numbers. Mr. Johnson would be unable to call an early election without Labour’s backing.
“We’re still in that situation where there are all sorts of exits out of the burning building, but they all look locked,” said Tim Bale, a professor of politics at Queen Mary, University of London.
The biggest hangup for the anti-Brexit camp in recent weeks has been the question of who would take over a so-called government of national unity if lawmakers succeeded in ousting Mr. Johnson in a vote of no confidence after lawmakers returned from summer recess next week.
Mr. Corbyn, who leads the biggest opposition party, nominated himself this month as caretaker prime minister, promising to avert a no-deal Brexit and then call a general election to break the logjam in Parliament.
But centrist lawmakers from smaller opposition parties like the Liberal Democrats abhor his left-wing economic policies and, in light of Mr. Corbyn’s longtime euroskepticism, distrust his views on Brexit. They would prefer to install a temporary prime minister who has no designs on permanently moving into the job. And Conservative lawmakers opposed to a no-deal Brexit — who were conspicuously absent from Tuesday’s meeting — also want no part in helping Mr. Corbyn take over.
So Labour leaders decided in recent days to pass on the idea of a no-confidence vote, reasoning that calling and then losing one next week would weaken Mr. Corbyn, British news reports said. Instead, Labour will hold that strategy for later, in case the legislative plan fails.
“We agree we will work together to stop a no deal #Brexit by legislation,” Anna Soubry, the leader of the centrist Independent Group for Change, said on Twitter after the meeting.
A statement released by the group of opposition lawmakers after the meeting positioned a no-confidence vote as a fallback option.
“The attendees agreed on the urgency to act together to find practical ways to prevent no deal, including the possibility of passing legislation and a vote of no confidence,” it said.
Proposing an anti-Brexit bill could quickly lead to fireworks in Parliament. Lawmakers did not release details on Tuesday, but the bill might require Mr. Johnson to ask Brussels for another Brexit extension, mirroring a plan that lawmakers forced on his predecessor, Theresa May, early this year.
Any such plan would depend on European leaders accepting an extension — no sure thing, as patience is wearing thin on the Continent — and anti-Brexit lawmakers have not made clear how they would make use of a delay. Mr. Johnson has also entertained using aggressive tactics, like shutting down Parliament, to pull Britain out of the European Union.
On Tuesday, Mr. Johnson spoke by phone with European Commission President Jean-Claude Juncker, who told him the bloc “will do everything it can to avoid” a no-deal Brexit, a spokeswoman for the commission said.
But first, anti-Brexit lawmakers will have to decide how to pass such a bill. They could try to tack an amendment onto a government report in September, but that might not be legally binding.
Or they could try to rip control of what happens in Parliament from Mr. Johnson’s government, as they did briefly in March to Mrs. May to test support for different Brexit plans. Lawmakers could then use that power to try to pass a law forcing Mr. Johnson to extend the Brexit deadline.
But taking control of parliamentary business is a tall task. Lawmakers may end up leaning once again on precedent-breaking decisions by John Bercow, the speaker of the House of Commons, who made himself a hero of the anti-Brexit cause this year for defending Parliament’s right to intervene in the Brexit debate.