Conservative rebels remain on a collision course with Theresa May’s government after former attorney-general Dominic Grieve gave a strongly worded speech in the House of Commons insisting he would not back down.

As Tory MPs clashed repeatedly with each other in a spiky debate on the latest stage of the European Union (withdrawal) bill, Grieve said he was determined to push his amendment to a vote, threatening the prime minister with a possible defeat.

In a half-hour speech, Grieve warned that the bill as it stood would unleash “a form of constitutional chaos” by allowing ministers to bypass parliamentary scrutiny.

He said he had sought at all times to engage with ministers to find a compromise, but without success: “The blunt reality is, and I’m sorry to have to say this to the house, I’ve been left in the lurch, as a backbench member trying to improve this legislation.”

In these circumstances, Grieve said, he felt obliged to vote in favour of his amendment, and if that did not pass, to vote against the government on the wider bill.

He said: “Apart from HS2 I don’t think I’ve ever rebelled against the government in my 20 years in this house.

“I do find it quite entertaining that some who criticise me for speaking my mind on this matter are individuals who appear to have exercised the luxury of rebellion on many, many occasions.

“But that having been said there’s a time for everybody to stand up and be counted. As Churchill said, he’s a good party man, and he puts the party before himself and the country before his party. And that’s what I intend to do.”

Tory whips have been pressing backbenchers to reject the Grieve amendment. Relations with the “mutineers”, as they were dubbed by the Daily Telegraph, have deteriorated so much that some were even threatened with legal action if they made false public remarks about the activities of the government’s whips.

At least one potential mutineer was warned by the chief whip, Julian Smith, that they could be sued if they made defamatory comments about the whips’ activities.

Another backbencher described the approach of the whips, who are responsible for party discipline, as “bullying junior MPs”.

Grieve and his fellow potential rebels appeared not to have been satisfied by a concession on Wednesday morning from David Davis, who tabled a written statement promising Conservatives a vote on the Brexit deal “as soon as possible” after negotiations are concluded.

Davis said: “The government has committed to hold a vote on the final deal in parliament as soon as possible after the negotiations have concluded. This vote will take the form of a resolution in both houses of parliament and will cover both the withdrawal agreement and the terms for our future relationship.”

He also promised that the vote on May’s Brexit deal would take place before any part of the withdrawal agreement was implemented: a pledge repeated by May at prime minister’s questions.

At PMQs at lunchtime, Conservative MP Anna Soubry, another rebel, challenged the prime minister, saying they were both “proud of being called bloody difficult women”, but urging her to accept Grieve’s amendment, “in a spirit of unity of everybody here and in the country”.

But May replied that “as currently drafted” Grieve’s amendment would prevent the government using key powers to prepare for Brexit and “could mean that we are not able to have the orderly and smooth exit from the European Union that we want to have”.

Rebels were being called into No 10 on Wednesday in a last-ditch attempt to allay their concerns – but several indicated to the Guardian they were not satisfied with Davis’s promise. Discussions between Downing Street and the rebels are ongoing, with the government not ruling out backing a reworded amendment or laying its own as a compromise.

Nicky Morgan, Heidi Allen and Antoinette Sandbach, as well as Soubry, said they had not been placated by the government’s latest move. They want a legally guaranteed vote on the draft agreement before Brexit day on 29 March 2019.

George Freeman, the Norfolk MP who stepped down recently from the PM’s strategy board, signalled that he was prepared to back the amendment, tweeting, “very much hope ministers will listen” to Grieve.

Grt to hear PM restate that Parliament will have a proper vote on the final Brexit deal. This pm the House will be scrutinising the Bill to that effect. V much hope Ministers will listen to distinguished @Conservatives former AttorneyGen & SolicitorGen on Amndnt7 #PMQs — George Freeman MP (@Freeman_George) December 13, 2017

Rebels had been expecting the government to table its own amendments that would put the pledge of a meaningful vote on the final deal into law, rather than relying on a promise from Davis or May.

Soubry told the Guardian: “Most of the so-called mutineers are lawyers – we understand the importance of statute.” She added: “We raised this with the prime minister in September. We said we don’t want to cause trouble. We don’t want to vote against the government. Dominic Grieve is not some headbanger.”

Wednesday’s vote is expected to be extremely tight. It could only need around eight rebels because the Conservatives only hold a majority of 15 with the help of Democratic Unionist party MPs. However, an unpredictable factor is how many of the seven Brexit-supporting Labour MPs are prepared to vote with the government.

If May is defeated, it would represent the first major Commons rebellion over the EU withdrawal bill.

The showdown comes as she prepares to travel to Brussels on Thursday for the European council meeting, at which EU27 leaders are expected to confirm “sufficient progress” has been made to allow negotiations to move on to Britain’s future relationship with the EU.

Grieve objects to clause 9 of the EU withdrawal bill, which hands ministers so-called Henry VIII powers to enact the Brexit legislation without a parliamentary vote. His amendment would not allow that to happen until MPs and peers had voted in favour of a fresh piece of legislation.

“The government has not come up with a legislative alternative to amending clause 9, but it must be amended,” he said, “because it is incompatible with the government’s own stated position as to how the final withdrawal agreement will be agreed by parliament.”



In the debate on the bill that followed PMQs, Tory MPs from different sides of the Brexit debate – including Jacob Rees Mogg and Oliver Letwin – suggested one solution might be for the government to completely withdraw clause 9, the controversial aspect of the bill.





The shadow Brexit secretary, Keir Starmer, confirmed on Wednesday morning that Labour would back the Grieve amendment, whipping opposition MPs to vote in favour of it. This makes it much more likely to result in a government defeat if the vote goes ahead.