Nicola Sturgeon, the leader of the Scottish National Party, told Jo Swinson of the Liberal Democrats that she should rethink her rejection of the proposition, which the latter had described as “nonsense”.
Sturgeon on Thursday signalled her 35 MPs could support Corbyn’s plan for a no-confidence vote in the government of Prime Minister Boris Johnson; extension to the October 31 deadline for the UK to leave the European Union; and a general election with the Labour leader as temporary prime minister.
Welsh party Plaid Cymru also suggested it could support the Labour proposal, while some rebels in Johnson’s Conservatives suggested they would at least meet Corbyn.
But Dame Caroline Spelman, a senior Conservative in favour of the UK remaining in the bloc, and the Independent Group for Change refused to support any Corbyn government.
So did Swinson, who called for a “less divisive” figure to form a unity government, such as veteran MPs Ken Clarke or Harriet Harman.
“There is no way [Corbyn] can unite rebel Conservatives and Independents to stop Boris Johnson,” said Swinson, who gained her 14th MP on Wednesday as Sarah Wollaston defected to the Liberal Democrats from the Independent Group, having previously defected from the Conservatives.
“It is not even certain that he would secure all the votes of Labour MPs.”
But Sturgeon said the Lib Dems “should rethink”, adding: “Jeremy Corbyn’s suggestion is not the only possible option – but given the circumstances, nothing should be ruled out at this stage.”
The SNP leader told the BBC: “It’s no secret, I’m not the greatest fan of Jeremy Corbyn, but we won’t rule out any option if it helps avert what is a looming catastrophe of a no-deal Brexit.”
Green MP Caroline Lucas also called on Swinson to rethink in a personal appeal, which she recorded in a video on Twitter: “Please join us in engaging with Corbyn to see if we can find a way forward.”
Swinson, in a letter, later offered to meet Corbyn “in the coming days” to discuss how their parties could work to stop a no-deal Brexit, but reiterated her belief that it must be someone else who leads an emergency government.
Corbyn proposed forming a government on a “strictly time-limited” basis to prevent a sudden departure under Johnson, hoping he could win over his personal critics to support the anti-no-deal cause.
But the reaction was mixed, with the five-strong Independent Group for Change flatly rejecting it.
Leader Anna Soubry said Corbyn “is not the person, given he struggles to maintain the confidence of his own backbenchers”.
Dame Caroline also said she could not support the proposal, nor a vote of no confidence in her own government.
“I could not support a Corbyn government, end of,” she told the Birmingham Mail.
Plaid Cymru’s Westminster leader Liz Saville Roberts offered her cautious support, saying the party was open to a unity government regardless of who leads it.
Corbyn appeared to have convinced some of his opponents within his party on the basis of blocking no-deal.
Backbench MP Wes Streeting said the Liberal Democrats were “wrong to reject” the offer, saying it should be “treated seriously” by everyone trying to stop the prospect of the UK leaving the bloc without an agreement amid warnings that this would lead to a “severe” economic downturn.
Remain-backing Conservative MP Guto Bebb was lukewarm about whether it was the right move, but told BBC Radio 5 Live he would “consider anything that avoids the pitfall of a no-deal Brexit”.
“It’s certainly an option which has been put on the table and should be at least considered,” he said.
Shadow business secretary Rebecca Long-Bailey appealed to critics by saying the move was “not about implementing Labour policy” but about avoiding the “unfathomable” damage a no-deal could cause.
Corbyn announced the plan in a letter on Wednesday to opposition leaders and Conservative MPs Dominic Grieve, Sir Oliver Letwin and Dame Caroline.
A letter being circulated and signed by the trio said they were willing to meet Corbyn and other opposition parties to discuss no-deal prevention options.
It also featured Dame Caroline’s name, despite her clear opposition to a Corbyn government.
Former Attorney General Grieve said a national unity government led by Corbyn was a “most unlikely way forward”, noting the Labour leader has views which are “entirely abhorrent” to him.
He said he was happy to speak to Corbyn about ways in which they might “cooperate” to stop a no-deal Brexit, adding: “Even for a short period a prime minister in a caretaker capacity has got to be somebody who can inspire trust – and such people do exist within the House of Commons and would be in a position to do that.
“I have to say that seeing Jeremy Corbyn’s history, it’s difficult to see how he could possibly be in a position to do such a thing.”
The Labour leader said he would seek a no-confidence motion soon after the House returns from its summer recess on September 3. This would need the support of the majority of MPs.
He would then seek an extension to the Article 50 process to delay the UK leaving the EU past the October 31 deadline.
Then, as prime minister, he would table a motion for an early general election which would succeed with the support of two-thirds of the seats in the Commons, in the same fashion as former Prime Minister Theresa May’s vote in 2017.
Corbyn said Labour would campaign in that election for a second referendum on EU membership with the option to remain in the bloc being available to voters.