LONDON — Britain’s Prime Minister Theresa May on Tuesday bowed to overwhelming pressure to reduce the risk of a disorderly departure from the European Union, accepting that Parliament should have the chance to delay Britain’s exit if it rejects her withdrawal plans next month.
Mrs. May’s concession, in the face of an internal rebellion, was the latest in a long line of retreats as she has struggled to cajole her fractious party into supporting a revised version of the deal on withdrawal, or Brexit, that lawmakers threw out by a massive margin last month.
Mrs. May’s hand was forced by rebels in her own Conservative government, who had threatened to vote on Wednesday for an amendment that could force her to request an extension of Brexit talks if she is unable to get her blueprint through Parliament.
In return for her promise of a vote on an extension, Mrs. May asked those rebels to wait once again, this time until March 12 at the latest, when she plans to bring her revised deal back to Parliament.
If lawmakers then reject the deal, she says, they should have the opportunity in the next two days to vote on whether to delay Brexit for a short time or to opt for a “no deal” departure — something that a large majority in Parliament opposes.
Mrs. May said that Britain would “only leave without a deal on March 29 if there is explicit consent for that outcome.” However, she added, “I don’t want to see Article 50 extended,” referring to the treaty section that governs the withdrawal process.
It remained unclear whether the offer would be enough to allow Mrs. May to avoid another parliamentary defeat on Wednesday; her opponents would in any case have expected a chance to try to amend the government’s plans during the crucial vote in March.
And while her move lessens the risk of a potentially disastrous “no deal” Brexit on March 29, Britain’s scheduled departure date, it is unclear for how long that danger would be staved off. A postponement of the Brexit date would also require the consent of all 27 other European Union governments.
Nevertheless, the announcement is an acceptance of the strength of opposition in Parliament to leaving without an agreement.
Until Tuesday, Mrs. May had insisted that the possibility of Britain leaving the European Union without an agreement and the damage that such a move could do to continental economies gave her crucial leverage in negotiations with the bloc.
This was the latest in a long line of tactical retreats made by Mrs. May as she pushes the moment of decision on Brexit closer to the deadline. Critics accuse her of running down the clock in the hope that Parliament will vote for her unpopular deal as the only way to avoid the worse fate of a cliff-edge departure.
The opposition leader, Jeremy Corbyn, seems to have been stringing his Labour Party along too, on Monday declaring his support for a second referendum on Brexit that many in his party favor. But most analysts say there is little chance Parliament will support the measure.
For Mrs. May, her concession on Tuesday was unusual to the extent that it followed a rebellion not by the perennially troublesome right-wing pro-Brexit faction in her party, but by the more pragmatic pro-Europeans. Last week three Conservative lawmakers quit the party to join a group of eight rebels from Labour, sitting together as an independent group.
But further Conservatives, including ministers, are appalled at the damage being inflicted on the economy by the uncertainty caused by Brexit and are determined to stop an ill-prepared business sector plunging over the cliff edge next month.
They have been agonizing on what to do on Wednesday when Parliament is expected to vote on an amendment crafted by a Labour lawmaker, Yvette Cooper, and a Conservative veteran, Oliver Letwin, that aims to prevent Britain lurching into a possibly chaotic exit without an agreement.
If it succeeds, Mrs. May would have until March 13 to get a Brexit deal approved but, failing that, Parliament could force her to request an extension in the withdrawal talks under Article 50 of the European Union treaty.
Normally, ministers who voted against the government would either resign or be fired.
A similar amendment failed by 23 votes last month, but since then the mood has darkened as exit day approaches and some jittery businesses have started to bolt the country, so defeat for Mrs. May is a real prospect.
On Saturday, three cabinet ministers — Amber Rudd, the work and pensions secretary, Greg Clark, the business secretary, and David Gauke, the justice secretary — dropped a heavy hint that they might vote for the amendment.
On Tuesday three less senior ministers, Richard Harrington, Margot James and Claire Perry, warned that they were prepared to do so, if Mrs. May failed to exclude the possibility of no deal.