Remain-supporting Tories have hinted that they could favour installing Jeremy Corbyn as an interim prime minister over a no-deal Brexit.
The Labour leader reached out across the political divide to gain support for his plan to lead a caretaker government.
His proposal was given a boost as the Conservatives he wrote to agreed to talks on how to stop the UK crashing out of the EU.
They stopped short of giving Mr Corbyn’s offer their full backing, but Guto Bebb, who quit as defence minister last year to back a second referendum, said he was open to the idea of an emergency government run by the opposition leader.
I think that those who have said they will do anything necessary to stop the long-term damage of a no-deal exit must take seriously this type of offer, said Mr Bebb, who was not approached by Mr Corbyn.
The Tories written to by Mr Corbyn were the former cabinet ministers Dominic Grieve, Sir Oliver Letwin and Dame Caroline Spelman. Nick Boles, who now sits as an independent after leaving the party over its handling of Brexit, was also contacted.
Their joint reply stated: We agree that our common priority should be to work together in parliament to prevent no-deal Brexit and welcome your invitation to discuss the different ways that this might be achieved.
Liberal Democrat leader Jo Swinson wrote to Mr Corbyn to suggest the pair meet “in the coming days” to discuss how their parties could work to stop a no deal, but reiterated her belief that it must be someone else who leads an emergency government.
Mr Corbyn’s proposal involves a no-confidence vote in Prime Minister Boris Johnson, an extension to the Brexit deadline beyond October 31 and general election with him being installed as temporary leader
The SNP and Plaid Cymru suggested they could support the plan, while some Tory rebels indicated they would hold talks with Mr Corbyn. But senior Tory Remainer Dame Caroline Spelman and the Independent Group for Change refused to support any Corbyn government.
Transport Secretary Grant Shapps also challenged Tory MPs to think very carefully about how they proceed in response to the unity government idea.
He told reporters: I think it’s absolutely extraordinary that any Conservative MP considered even for one minute installing Jeremy Corbyn in Downing Street.
Jeremy Corbyn would wreck our economy, he would destroy jobs and the livelihoods, savings, I think he also can’t be trusted with security or crime and … I just think that any Conservative should think very, very hard about doing this. It actually presents a very clear choice.
You either have Jeremy Corbyn as prime minister overturning the result of the referendum or Boris Johnson respecting the referendum, putting more money into the NHS, more police on the streets to keep us all safe.
As the different Remain factions split over the issue, Mr Johnson used Twitter to repeat his Brexit plan. He wrote: The referendum result must be respected. We will leave the EU on 31st October.