Meanwhile, in a letter leaked to the The Mail on Sunday, two cabinet secretaries, Michael Gove and Boris Johnson, have pressed Mrs. May to begin preparing to leave the European Union in the absence of any transition agreement. They urged her to set a firm date of June 30, 2021, for that to happen.
She also faces a frontal challenge from the Labor leader, Jeremy Corbyn, who has called her too weak to stand up to “no-deal extremists” within her own party.
“This is now crunchtime,” Keir Starmer, Labor’s Brexit spokesman told the BBC early on Monday. “I think it’s blindingly obvious to everyone who is following the negotiations that the final agreement with the E.U. is not going to have been agreed by March of 2019, and we need a bridge, or transitional arrangements.”
Mr. Starmer welcomed the news that Parliament would be allowed to vote on the agreement, and said the government must accept a range of further amendments that Labor lawmakers would propose on Tuesday, in an effort to protect British jobs. “This is a significant climb down from a weak government on the verge of defeat,” Mr. Starmer told lawmakers.
Labor lawmakers pointed out that the concession does not give Parliament power over a “no deal” scenario urged by right-wing Tories, in which Britain would leave the bloc with no transition agreement. “Parliament would be effectively sidelined, which makes a mockery of parliamentary sovereignty,” Chuka Umunna, a Labor lawmaker, said on Twiitter. “He calls it a meaningful vote — it is a fake one.”
Mrs. May also faced pressure on Monday from European business leaders, who urged her in a meeting at No. 10 Downing Street to avoid a “cliff edge” exit by agreeing to remain in the customs union and the single market.
Martin Wansleben, the head of Germany’s chambers of commerce, warned that the automotive industry would face more than $2.3 billion in additional tariffs annually if trade between the United Kingdom and the European Union fell under World Trade Organization regulations.
The concession marks the latest blow to Mrs. May, who became prime minister in June 2016, in the aftermath of the Brexit referendum. Her authority has corroded steadily in recent months. Last week saw the resignation of two of her cabinet ministers, and at least two more are under pressure to step down.