Sixty Labour MPs are ready to support a national unity government – even if it is led by a Tory PM.
But that still may not produce the numbers to topple Prime Minister Boris Johnson next month.
One shadow minister said: “It would only be enough if you could get the SNP on board.
“And they are unlikely to do anything to prop up any British government.”
A rebel alliance led by former Chancellor Phil Hammond wants to bring down the PM in a no-confidence vote next month to stop a no-deal Brexit.
If successful, a caretaker government led by an interim PM would be formed and postpone leaving the EU until a General Election had been held.
Names in the frame include veteran Tory Ken Clarke, 79, the longest serving MP.
Fellow Tory Sir Oliver Letwin is another possibility, as are Labour’s Hilary Benn and Yvette Cooper.
Jeremy Corbyn is opposed to any deal that would not make him PM.
But Tories would refuse to vote the Labour leader into Downing Street. Yet only by combining can they be certain of having a majority of MPs.
It would give Mr Corbyn the General Election he wants – while stopping the no-deal Brexit he is ferociously against.
Both sides are now frantically working to get enough MPs into their teams.
Labour’s Steve Pound said: “It is like a Rubik’s cube at the moment – when you can get one side lined up you lose the others.”
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