The Liberal Democrats have no objection in principle to supporting Jeremy Corbyn as an interim prime minister, party sources have said.

Jo Swinson’s opposition to the Labour leader heading up a government of national unity is purely “pragmatic", they insisted, amid a backlash over her rejection of the idea.

One Liberal Democrat MP suggested that the party would support Mr Corbyn becoming prime minister if he managed to build a majority in the Commons to stop a no-deal Brexit.

And a party source told The Independent that the Liberal Democrats did not any have “principled objection“ to the Labour leader entering No10 with the purpose of stopping no-deal.

The decision to open the door to helping Mr Corbyn become prime minister marks a significant softening of the Liberal Democrats' stance, after Ms Swinson, the party's leader, dismissed the idea as "nonsense" earlier this week.

However, the party challenged Labour to explain how it could build a governing coalition, given opposition to its leader from across the Commons.​

Liberal Democrat MP Christine Jardine suggested that the party would support a government of national unity led by Mr Corbyn if he could secure enough support among MPs.

She told BBC Radio Scotland: "I'm never going to support a no-deal Brexit. That would be crazy. I'm never going to support that if there is an option on the table for a government of national unity to have a People's Vote, to get us out of this mess, then have a general election - an interim emergency government, if there is a successful [prospect of it happening]."

She added: "If somehow, miraculously, the House of Commons changes its mind about Jeremy Corbyn and backs him, then there is no way that I am going to do anything to stop the House of Commons getting us out of this mess."

"But the reality is he does not have the numbers."​

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A Liberal Democrat source told The Independent that the party's opposition to Mr Corbyn becoming prime minister was “not a principled objection, it’s pragmatic one“ and insisted there was “no way“ they would refuse to support the Labour leader in a confidence vote if he had shown that he could command a majority.

Asked if they would back Mr Corbyn if he managed to assemble a governing coalition, they said: “There’s absolutely no way that the Liberal Democrats would allow nodeal if there was going to be a vote and he was going to win. There’s no way the Liberal Democrats would stop that.

“There is no prospect of the Liberal Democrats enabling no-deal if there was going to be a government of national unity that was going to stop it.“

However, the party believes that the prospects of Mr Corbyn leading an interim government are virtually nil, given that a number of opposition MPs have said they would not support him entering No10.

Change UK's five MPs are staunchly opposed to the Labour leader, as are independent MPs Heidi Allen and Ian Austin.

It means that Mr Corbyn would need the support of some Conservatives in order to secure a majority in the Commons.

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Ms Swinson, the Liberal Democrat leader, insisted on Friday that this meant Mr Corbyn’s plan to step in as interim prime minister in order to stop a no-deal Brexit and then trigger a general election had “no chance of success“.

She told BBC Radio 4's Today: “We've already had seven or eight MPs on the opposition benches saying they couldn’t support his leadership of a caretaker government - the Change UK MPs have made that clear, Ian Austin, Heidi Allen..​.

“People in No 10, Dominic Cummings, Boris Johnson, will be rubbing their hands at the fact that we are talking about a plan here that has no chance of success."

She added: “Even if Liberal Democrats did support Jeremy Corbyn, the numbers don’t stack up because of those eight MPs on the opposition benches, [plus] about ten MPs who have left the Labour Party because of Jeremy Corbyn’s leadership who are sitting on the opposition benches, many of whom I think are unlikely to support him.

“For every one of those he needs to get a Conservative MP to back him in this way. Those Conservative MPs are very clear that they’re not about to put Jeremy Corbyn in No10."

Ms Swinson suggested that a government of national unity should be led by a senior parliamentarian such as Tory grandee Ken Clarke or Labour’s Harriet Harman.

She challenged Mr Corbyn to explain which Tory MPs he believed would back him in a confidence vote.

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It came as the Liberal Democrat leader faced a backlash after dismissing Mr Corbyn's suggestion that he could lead a temporary government to stop a no-deal Brexit as “nonsense“.

Leaders of other anti-Brexit parties urged her to rethink her position.

Asked about the Liberal Democrats’ objection, SNP leader Nicola Sturgeon said: “I think that’s daft, frankly, for someone who professes to be so against Brexit.

“On the Remain, anti-no deal Brexit side, we should be looking at all options and I’m not prepared to rule out anything before we’ve had the opportunity to explore it.“

And Caroline Lucas, the Green Party’s Westminster leader, made a “personal appeal“ to Ms Swinson, saying: “We need to stop Boris Johnson, we need a People’s Vote. Please join us in engaging with Corbyn to see if we can find a way forward.