MPs are set to vote on legislation that could block efforts by the next prime minister to force through a no-deal Brexit by suspending Parliament.
It comes after the House of Lords backed the measure by a margin of 103 votes on Wednesday evening.
Tory leadership frontrunner Boris Johnson has not ruled out suspending Parliament to ensure the UK leaves by 31 October, even without a deal, if he becomes prime minister.
His rival Jeremy Hunt has ruled it out.
If the 31 October deadline is reached without Parliament backing an agreement between the UK government and the EU, the UK is scheduled to leave the EU without a deal.
MPs have consistently voted against a no-deal Brexit, but the prime minister could try to get around that by suspending Parliament – proroguing – in the run-up to the deadline, denying them an opportunity to block it.
But the House of Lords’ amendment to the Northern Ireland (Executive Formation) Bill would require progress reports on restoring devolved government in Northern Ireland to be debated regularly in Parliament, effectively preventing it being shut down.
It builds on an amendment from pro-EU Tory Dominic Grieve passed by MPs last week that would require ministers to give fortnightly reports to Parliament throughout October on progress to restore devolution.
The new Lords amendment would ensure these have to be debated in the weeks before the Brexit deadline – meaning MPs and peers have to sit.
But this tweak will have to be approved by MPs on Thursday in order to make it into the final version of the bill.
Another amendment – that explicitly blocks suspension between 9 October and 18 December unless an executive in Northern Ireland is formed – has also been selected by the Commons Speaker John Bercow for consideration.
Former foreign office minister Alistair Burt, who is supporting this amendment, along with Brexit committee chairman and Labour MP Hilary Benn, said this change would further strengthen the measures against the suspension of Parliament.
He said it was “in order to make sure that we reflect the views of our constituents by being here (in Parliament)”.
‘Show common sense’
Justice Secretary David Gauke, an opponent of a no-deal Brexit, told BBC Radio 4’s Today programme that proroguing Parliament would be “outrageous”, but did not confirm whether he would back measures to block it.
“I completely understand the concerns a number of my colleagues have raised about the idea that parliament should be suspended in the autumn at a crucial juncture in this country’s history” he said.
“I very much hope that Parliament won’t be prorogued and I understand why colleagues are taking action today.”
Pressed on whether he would resign from the government to vote in favour of the change to the Northern Ireland Bill, he replied: “I’ve said what I’ve said and you can interpret that as you wish.”
Former education secretary Justine Greening tweeted: “Important votes on Northern Ireland Bill later today. Time for all MPs to show some common sense and keep Parliament open as normal in September and October.
“Brexit needs resolving and only Parliament can break the deadlock. Today’s the day to stop prorogation.”
Former Tory prime minister John Major has said he will seek a judicial review if the next prime minister tries to suspend Parliament.
Campaigner Gina Miller has threatened the same action.
At Conservative Party leadership hustings, when asked about suspending Parliament, Mr Johnson said he would “not take anything off the table”.
He said he wanted to leave the EU on 31 October “come what may”.
Downing Street said forcing a report and debate every two weeks “risks being counter-productive” to the aim of restoring the executive in Northern Ireland.
The prime minister’s official spokesman told a Westminster briefing: “We have been very clear that the purpose of this bill is to ensure the continuation of vital public services and effective governance for the people of Northern Ireland.
“In the light of the ongoing talks to restore the executive, our view is that forcing a report and debate every two weeks on the progress of those talks risks being counter-productive to this overarching aim.”