The prime minister has agreed to the showdown, in February 2019, to avert a threatened revolt by pro-EU Tory rebels after talks today, The Independent has learned.
Full details of the amendment to be tabled to the EU Withdrawal Bill will be published later, ahead of a 5pm deadline for debating it in the House of Lords on Monday.
“Deal or no deal parliament will have a meaningful vote and to be clear there will be no hard #Brexit when the EU Withdrawal Bill is passed.”
Mr Grieve, the former attorney general leading the revolt, had insisted that MPs must have the power to prevent a “no deal” – threatening Ms May with defeat next week if she refused.
He was also pushing to force the government to give MPs a decisive say on the next steps if the talks are still deadlocked at the end of November – or if the Commons has rejected a deal.
It was unclear whether that part of his amendment would survive in the fresh text to be put forward for next week’s clashes.
The prospects of leaving with no deal had appeared to be receding, amid criticism of the government for failing to prepare for border queues and warnings of shortages in shops and hospitals.
One senior Tory, foreign affairs committee chairman Tom Tugendhat, claimed a protection was unnecessary because the prime minister would be toppled anyway if there was no deal and there would be “a new government”.
But No 10 alarmed the rebels, when a spokesman said: “We have to be in a position to honour the result of the referendum in all circumstances.”
There was no confirmation from No 10 of what had been agreed in the talks with backbenchers, ahead of publication of the new amendment.
In a sign of caution among the rebels, Mr Grieve’s original amendment was set to re re-tabled in the Lords, to give them continued leverage over the government.
One part would require ministers to obtain approval from MPs on what happens next if no agreement has been reached in Brussels by 30 November
A further, tougher clause would then force the government to follow any “direction” given by MPs if there is no agreement by 15 February.