Senior Labour and Conservative MPs leading the battle to stop a no-deal Brexit are focusing on passing a “radical” new law to block it, after concluding that there is no imminent prospect of toppling Boris Johnson and installing an emergency government.

Last week was punctuated by rows among MPs over who should lead a temporary government to stop a no-deal Brexit, with the Lib Dems and other MPs refusing to back any move that would put Jeremy Corbyn in No 10.

However, those planning to use legislation to stop the UK crashing out of the EU believe there is a growing majority for their plans and think No 10 will be unable to stop them.

Shadow cabinet members and cabinet ministers who departed with the arrival of Johnson are among those backing the strategy in preference to a no-confidence vote in the prime minister. They believe the hardline tactics deployed by Dominic Cummings, who ran the Vote Leave campaign and is now the prime minister’s key adviser, have swelled the numbers prepared to act.

“This is not the time for boring and neutral tactics,” said one figure involved. “This isn’t a time for typical deference. These people will show no deference and give no quarter – and we need to be just as ruthless and organised as they are.”

A senior Labour figure said: “People are slightly barking up the wrong tree. My strong view is that there is a clear majority to try to stop no deal. It’s stronger now because those coming out of the cabinet are undoubtedly swelling the numbers, but also swelling the morale on the Tory side to do something. It feels like the majority is stronger than it was and the determination is stronger.”

Dominic Grieve. Photograph: Simon Dawson/Reuters

A third figure said: “For my money, I don’t think a no-confidence vote will be particularly winnable in early September – even some opposition MPs wouldn’t back it. Why go for that when there’s a more direct route?”

MPs plan to pass a law stating that the prime minister must request a delay to Brexit to avoid a no-deal outcome. However, their challenge has been to find a parliamentary device enabling them to do so. There are no guarantees of success, but tactics include amending a vote relating to the Northern Ireland executive, altering parliament’s standing orders, and using an emergency debate to seize control of the parliamentary timetable – which is not usually allowed under parliament’s current rulebook.

The stakes are high. Dominic Grieve, a Tory MP who has been a leader of the efforts, said that he had received death threats as a result of Johnson’s Brexit rhetoric.

Downing Street is said to be holding daily meetings about how to delay legislation in September – a tactic designed to take away opportunities for MPs to hijack government plans with measures opposing no deal. However, rebels already believe they can act without any legislation being presented by the government. “They are planning on how to take away any hooks, but we don’t need hooks,” said one of those involved.

Some insiders have been pleased that much public attention has been focused on the idea of a government of national unity, which took the spotlight off their plans to seize control of parliament and pass an anti-no-deal law next month. Others are also happy that ideas are being stressed-tested now. One former minister said: “I don’t think it’s a bad use of the summer for unworkable ideas to be aired, scrutinised and dismissed.”

Jo Swinson Photograph: Tolga Akmen/AFP/Getty Images

The row over who should lead a unity government following a no-confidence vote in Johnson’s administration was ignited when Jo Swinson, the new Lib Dem leader, rejected Corbyn’s offer to lead a temporary government as “a nonsense”. Swinson has since softened her rhetoric.

Corbyn’s letter offering to lead a temporary government came after Tom Watson, Labour’s deputy leader, and Swinson discussed cross-party efforts to stop no deal. “It was absolutely the right thing for Jeremy to do and forced the Lib Dems into an error,” said a Labour MP usually critical of Corbyn.

Most accept that, while Swinson was too dismissive of Corbyn’s offer, she was right to conclude that a Corbyn-led emergency government was a non-starter. Opponents of no deal calculate that at least eight Tory rebels would be needed, and some of the most likely have already this ruled out.

MPs in all parties are already discussing ways of sidelining Corbyn by seeing if there is enough support for a unity leader, such as Harriet Harman or Ken Clarke, who would not require the support of Labour’s front bench. Ultimately, several Labour MPs believe Corbyn will back a unity figure if his own attempt to form a government has failed and no deal looms.

“He’ll get a bite of the cherry – no one can stop him trying to form a government,” said one MP. “The real issue is, after that, will he make way or see no deal happen? That is coming down the road.”

Meanwhile, many Conservatives still hope Johnson will return to the Commons at the 11th hour with one last chance to vote for a Brexit deal similar to that offered by Theresa May. They believe Labour MPs opposed to a second referendum, such as Lisa Nandy, could be convinced to back it. While most are convinced that Cummings is prepared to leave the EU without a deal, some also expect serving ministers to rebel should such an outcome look imminent.

“I just think their inner Tory who cares about the economy will scream at ministers as it did for Theresa May,” said one former minister. “I think Cummings will be told ‘no’ and then sort of explode like a Dr Who dalek whose wires are fatally crossed, screaming ‘exterminate.’”

Stopping no deal





Corbyn-led temporary government

Jeremy Corbyn has offered to lead a temporary government tasked with requesting a delay to Brexit from the EU, before triggering an election.

Likelihood: one in five

Government of national unity

Jo Swinson, the Lib Dem leader, has said Corbyn cannot command enough support to lead a temporary government. She has instead suggested a temporary government of national unity, led by a more neutral figure such as Labour’s Harriet Harman or veteran Tory Ken Clarke.

Likelihood: two in five

New laws blocking no deal

MPs such as Dominic Grieve, Oliver Letwin, Nick Boles and Yvette Cooper have been part of efforts to pass new legislation that orders the prime minister to request a Brexit delay to avoid no deal.

Likelihood: three in five

A Brexit deal is agreed

Some MPs are still holding out hope that Boris Johnson will offer them a vote on a Brexit deal based on the agreement put forward by Theresa May. For it to pass, Labour MPs opposed to a second referendum, such as Lisa Nandy, would have to back it.

Likelihood: two in five