MPS are likely to block a bid by Boris Johnson to hold a General Election in December later today.

But the prime minister could have been thrown a lifeline in the shape of a call by the Liberal Democrats and the SNP to go to the polls a week earlier than Mr Johnson had proposed.

The prime minister's bid to hold a General Election on December 12, be presented to Parliament today, is being made under the Fixed-Term Parliaments Act (FTPA), and requires a two-thirds Commons majority - 434 MPs - to pass. But Labour's lack of support for the proposal means it is likely to be defeated.

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But the Liberal Democrats and Scottish National Party have offered Mr Johnson a way out of the deadlock.

Lib Dem leader Jo Swinson and the SNP's Westminster leader Ian Blackford have put forward a tightly-drafted Bill that would grant an election on December 9 - three days earlier than the PM's suggested polling date - as long as the European Union grant an extension until January 31. The draft law, currently scheduled for Tuesday's sitting, would require a simple majority of 320 MPs to support it in order to dissolve Parliament - 114 fewer than under the FTPA "super majority" rules.

With the SNP and Lib Dems supporting the initiative, the bill is likely to pass even without Labour backing.

Downing Street indicated it could be willing to support the pro-Remain parties' proposals in a possible compromise offer.

A Number 10 source said if the government's request for an election was lost, "we will look at all options to get Brexit done including ideas similar to that proposed by other opposition parties".

If passed on Tuesday, the SNP-Lib Dem Bill is likely to achieve Royal Assent by Thursday and Parliament would be dissolved by the end of the week for the first December poll in almost a century.

Its quick dissolution turnaround period would mean the Withdrawal Agreement Bill - the attempt to put Mr Johnson's Brexit deal with the EU into law - would fail to pass before Hallowe'en.

The PM had said in the past he would prefer to be "dead in a ditch" than miss the October 31 deadline.

The EU appeared to pave the way for pro-Remain MPs to back Ms Swinson and Mr Blackford's proposition, with the Guardian reporting Brussels had agreed to Britain's request for an extension until January 31.

The UK would be able to leave earlier, with Brexit going ahead on the first day of the month after a deal is ratified, according to the newspaper.

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Scottish first minister Nicola Sturgeon took to Twitter to explain why the SNP was backing a December 9 election.

She said there was "no evidence" that a majority for a second referendum existed in Parliament and that it would be more embarrassing for the Conservative Party leader to have to fight an election before having delivered Brexit as promised.

"An election now would instead force him to explain his failure to keep his 31 October 'do or die' promise and also defend his bad deal," said the SNP leader.

Ms Swinson told the BBC's Andrew Marr programme: "We think we need to resolve this impasse. We think the best way to resolve it would be a 'people's vote' but, in the absence of proper Labour numbers to do that, a General Election would be the other way."

Labour looks unlikely to back the bill with leader Jeremy Corbyn saying, according to the Telegraph, that even with the Article 50 deadline pushed into next year, no-deal was "still there as a threat".