MPs are set for a crunch Brexit vote on Thursday after peers passed a plan designed to stop Boris Johnson suspending parliament to force through no deal.
The House of Lords set up a battle in the Commons by passing an amendment by 272 votes to 169, majority 103, aimed at ensuring parliament is sitting in the weeks leading up to the October 31 Brexit deadline.
MPs will now vote on the amendment amid fears that Johnson could prorogue - or simply dissolve - parliament in the weeks before Halloween to stop politicians passing laws to stop Britain leaving the EU without a deal.
The Tory leadership frontrunner has promised to deliver Brexit “do or die” by October 31, and has failed to rule out dissolving parliament to do so - a tactic which has been branded a “constitutional outrage”.
The cross-party group of MPs and peers has come up with a complicated plan to amend the Northern Ireland (executive formation) bill to make the government publish progress reports on the almost unrelated matter of power-sharing talks to restore the government at Stormont.
But crucially it includes the proviso that the reports would be accompanied by debates in Westminster in the weeks leading up to the Brexit deadline, meaning parliament must sit.
This would give MPs and peers the opportunity to use parliamentary tactics to stop no deal or even bring down the government if necessary.
All eyes will now turn to how many Remain-backing Tory MPs rebel in Thursday’s votes, which will be another test of whether there is a Commons majority against both prorogation and no deal.
Shadow Brexit secretary Sir Keir Starmer made clear Labour would support the amendment.
“This is another important step to prevent the suspension of parliament,” he said.
“We will do everything to support this measure in the Commons tomorrow.”
Seven Tory MPs backed a related amendment put forward by ex-cabinet minister Dominic Grieve last week, ensuring it passed by one vote.
But one Remain-backing Tory MP said more could follow on Thursday.
Meanwhile, independent former Tory MP Sarah Wollaston challenged pro-EU ministers who know they will be sacked by Johnson if he becomes PM next week to defy Theresa May’s orders and vote for the amendment on Thursday.
She told HuffPost UK: “All those government ministers who know for certain they will be leaving their jobs next week surely they could stop saying now isn’t the time - now is the time.
“It is for the better of the nation to put national interest ahead of party interest and I hope they will go to make a point rather than wait to be sacked.”
Later, Tory ex-minister Ed Vaizey, who last week abstained on the Grieve amendment, said he would vote for the Lords amendment or a potential additional amendment pushed by the ex-attorney general.
But he dismissed suggestions pro-EU ministers could resign to back the amendment.
“I don’t think ministers will resign tomorrow, I think they’ll simply wait to be sacked when Boris becomes prime minister and then the game to a certain extent moves to the next stage,” Vaizey told BBC Newsnight.