Theresa May faces one of the most critical moments in the Brexit process so far as she attempts to find a way of giving parliament a meaningful vote on the terms of the final deal that satisfies rebels on both sides of the party.

Downing Street sources indicated that the new amendment, which must be tabled on Thursday before the withdrawal bill returns to the Lords on Monday for its final stages, was not yet agreed.

Dominic Grieve, the leader of a group of Conservative Brexit rebels, started negotiations with officials on Wednesday afternoon, after the prime minister avoided defeat on his amendment on Tuesday by pledging to talk further on how a meaningful vote could work.

On Thursday morning, the Brexiter Jacob Rees-Mogg renewed the claim that Grieve and his allies were trying to stop Britain leaving the EU.



“The Commons is not and cannot be an executive body,” he wrote in the Times. Clause C of the Grieve amendment would have given parliament full control of the next steps in the process if there was no final deal by mid-February 2019.

It is unprecedented for parliament to have such a role, as the academic constitutional expert Vernon Bogdanor said in the Observer on Sunday.

Later on Thursday morning, the Brexit secretary, David Davis, will face questions in the Commons and is expected to be pressed by both sides on how the government plans to answer its critics.

His words will be picked over by both sides. There is cross-party support for Grieve, a former attorney general.

But on Wednesday, a Downing Street source appeared to suggest the government was not willing to discuss clause C of Grieve’s amendment.

Two of the putative rebels, Anna Soubry and Heidi Allen, quickly said that did not match their recollection of what had been promised, with Soubry urging the government to “sort it please”.

For the avoidance of doubt the PM said yesterday that clause c of Dominic Grieves amendment would be discussed as part of the new amendment to be tabled in the Lords. If the PM goes back on that there will be no agreed amendment that I can support #sortitplease — Anna Soubry MP (@Anna_Soubry) June 13, 2018

Later in the day, both sides said they were more hopeful of achieving a compromise, with Grieve describing the talks as “sensible”.

May is trying to walk a political tightrope between Grieve and his colleagues, who are anxious about the risk of a no-deal Brexit, and well-drilled agitators on the leave wing of her party, who are urging her not to make too many compromises.

Privately the Brexiters continue to insist the parliamentary arithmetic is less tight than the chief whip, Julian Smith, fears, and that the government can defeat the rebels without making major concessions.

At prime minister’s questions, May said the government intended to bring forward its own amendment, but stressed that she could not allow MPs to bind the government’s hands or to open it up to the risk that Brexit could be reversed.



“I am absolutely clear that I cannot countenance parliament being able to overturn the will of the British people. Parliament gave the decision to the British people, the British people voted to leave the European Union, and as prime minister I am determined to deliver that,” she said.

After prime minister’s questions, a No 10 source was asked whether her remarks meant that “as far as the government is concerned, clause C is not up for discussion as part of this amendment”.

The source replied: “I think that’s a fair assessment.”

Grieve and his colleagues insist they have no intention of seeking to overturn the referendum result.

Rees-Mogg, the chair of the pro-Brexit backbench European Research Group, said: “It is absolutely essential that the separation of powers should be observed and that it should be made clear in any compromise amendment that the job of the government and the job of parliament are different.”

A statement from the Department for Exiting the European Union said on Tuesday Davis had set three tests for any new amendment: not undermining the negotiations; not changing the constitutional role of parliament and government in negotiating international treaties; and respecting the referendum result.

The high stakes for May were underlined by warnings from the rebels that the promise made by the prime minister was “a matter of trust”.

The former education secretary Nicky Morgan said if a compromise amendment did not emerge, rebels could work with the Lords to ensure the changes took place.

“I think it would be fairly certain that one of the members of the House of Lords would find a way to put down Dominic’s original wording that couldn’t be voted on yesterday. So we are partway through discussions and there is more to come,” she said.

May was challenged by Jeremy Corbyn at PMQs over the government’s continued failure to make progress on deciding what post-Brexit customs arrangements it wants to negotiate for.

He sought to embarrass the prime minister by quoting several of the leaked comments made by the foreign secretary, Boris Johnson, at a private dinner for Tory donors last week.

“When the prime minister met President Donald Trump last week, did she do as the foreign secretary suggested and ask him to take over the Brexit negotiations?” the Labour leader asked, prompting a long pause from May and cheers from his own MPs.

May conceded that the government’s promised Brexit white paper would now not be published until July, after she has gathered her ministers together at her country retreat of Chequers for a second awayday to thrash out their differences.

Government sources said the cabinet breakout groups set up to discuss the two rival options for future customs arrangements had met this week, with little sign of any resolution.

Brexiters, including Johnson and Davis, are keen on the idea of a “max-fac” approach, using technology to avoid a hard border in Ireland, while colleagues including the chancellor, Philip Hammond, and the business secretary, Greg Clark, prefer a customs partnership.

Johnson and Hammond sat alongside each other on the frontbench for PMQs, just behind the prime minister, and Corbyn reminded her that Johnson had referred to the Treasury as “the heart of remain”.