BORIS Johnson is preparing to abandon a vote on his proposed Brexit deal if Conservative rebels and opposition parties succeed in passing a further delay to it in today’s Commons votes.

The Prime Minister opened a special Saturday sitting of the UK Parliament with a heartfelt plea, urging MPs to back his deal and “end this debilitating feud” to heal Britain.

But Jeremy Corbyn insisted his MPs would "not be duped" into supporting the Government’s “sell-out” Brexit deal, which risked “thousands of British jobs” while Ian Blackford for the SNP decried how Scotland had been “shafted” by a Tory premier, who did “not care about Scotland”.

However, despite his rallying call to colleagues, some Tories and some former Tories look set to support a move that could prolong the parliamentary deadlock.

John Bercow, the Commons Speaker, has accepted an amendment for debate and vote from Sir Oliver Letwin, the former Cabinet Minister, who wants any Brexit to be delayed until all of the necessary legislation to implement the Johnson Plan is passed.

Stressing he supports the new withdrawal deal, Sir Oliver says the move is simply an "insurance policy" to ensure the UK could not crash out of the EU without a deal on October 31.

With many of his fellow MPs who had the Tory whip withdrawn expected to back his amendment, the Government is facing a strong possibility of defeat later today.

It is believed Mr Johnson unsuccessfully urged Sir Oliver in a Downing St meeting last night to pull his amendment.

As he moved it in the Commons chamber, the backbencher claimed his proposal would prevent an unintended no-deal Brexit.

"The Prime Minister has a strategy, I fully accept that, and I accept that it is rational in its own terms. Is it that he wants to be able to say to any waverers: 'It's my deal or no-deal. Vote for the implementing legislation or we crash out?'

"Now I understand that strategy but we can't be sure that such a threat from the Prime Minister would work," claimed the Dorset MP.

"I, despite my support for the Prime Minister's deal, do not believe that it's responsible to put the nation at risk by making that threat,” he declared.

"So I'm moving this amendment to ensure that whichever way any future votes may go, today, or next week, or the week after, we can be secure in the knowledge that the UK will have requested an extension tonight, which if granted can be used if and to the extent necessary, and only the extent necessary, to prevent a no-deal exit," added Sir Oliver.

By 1pm, it was still not clear if the Letwin amendment would succeed.

If the Government does lose the vote on Sir Oliver's proposal, then it is expected not to push the changed motion to a vote, abandoning the process.

It is expected loyal Tory MPs will simply drift away; although a number will stay in the chamber to hear the PM give a post-vote Point of Order to explain what the Government would do in the face of an effective defeat.

The expectation is that Mr Johnson will, under the terms of the Benn Act, have to send a letter to Brussels asking for an extension. But he could write an accompanying note, setting out his personal opposition to the move.

The Government would then introduce the withdrawal legislation to implement the agreement next week in bid to get it through Parliament by the deadline of October 31.

The EU27 could withhold its decision on giving an extension pending the passage of legislation. But it is believed that the so-called Remain Alliance of MPs as well as pro-EU peers in the House of Lords would seek to delay completion of the legislation in order to have the chance of securing a further delay to Brexit.

While the likes of Emmanuel Macron, the French President, and Jean-Claude Juncker, the European Commission President, have suggested there will not be a further “prolongation,” others like Angela Merkel, the German Chancellor, and Donald Tusk, the European Council President, have suggested they would be willing to grant a further extension.

Of course, there are two other possibilities. The Letwin amendment fails and the Government wins the vote on its motion, which would mean Mr Johnson would not need to ask for an extension and the withdrawal legislation would then look set to move to completion by October 31.

The other possibility is the Letwin amendment fails and the Government motion also fails. Any defeat is likely to be by only a few votes, which would encourage the PM to make a few changes to help push the legislation through in another vote before October 31.

Early in the day, members of the public were queuing up to get a seat in the gallery for the Brexit debate. As the morning wore on hundreds of people began to gather in Parliament Square as part of the People’s Vote demonstration.

Inside, the Commons chamber was packed as Mr Johnson kicked off the first Saturday sitting on Parliament since the Falkalnds War in 1982.

He urged MPs to abandon the "delusion" that they could simply delay Brexit yet again.

"Whatever letters they may seek to force the Government to write, it cannot change my judgment that further delay is pointless, expensive and deeply corrosive of public trust," he declared.

"And people simply will not understand how politicians can say with one breath that they want delay to avoid no deal and then with the next breath that they still want delay when a great deal is there to be done.

"Now is the time to get this thing done, and I say to all members let us come together as democrats to end this debilitating feud."

With Mr Johnson's erstwhile allies in the DUP fiercely opposed to the proposed customs arrangements for Northern Ireland, the vote is likely to be close.

The PM insisted that his plan would meet the "special circumstances" in Northern Ireland and the need to maintain an open border with the Republic.

But DUP deputy leader Nigel Dodds called on him to honour his commitment to deliver Brexit for "the whole of the United Kingdom".

"Weariness in this House over Brexit should not be an excuse for weakness on Brexit or weakness on the Union," declared the MP for Belfast North.

With every vote potentially crucial, Mr Johnson sought to reach out to Labour MPs who have indicated they could back a deal, insisting he was committed to the "highest standards" of workers' rights and environmental protections outside the EU.

However he was accused by Mr Corbyn of making "empty promises" saying he had spent weeks secretly negotiating to have legally binding commitments in Theresa May's Brexit deal removed.

"This Government cannot be trusted and these benches will not be duped," the Labour leader insisted.

"Voting for a deal today won't end Brexit. It won't deliver certainty and the people should have the final say.

"Labour is not prepared to sell-out the communities we represent. We are not prepared to sell out their future. And we will not back this sell-out deal," he told MPs.

Mr Blackford was equally scathing about the Johnson Plan, saying: "The Prime Minister has returned from Brussels to present a deal that he knows, that we all know is actually worse than Theresa May's deal, a deal that would see Scotland shafted by this United Kingdom Government, left at an economic disadvantage, with Scotland's views totally disregarded by this Prime Minister and his Government.”

The Highland MP added: "Not a single MP who cares about Scotland's future should consider supporting the Prime Minister today."

In response, Mr Johnson accused Mr Blackford of being a “little bit churlish” as he had also not mentioned England or Wales.

"The reason of course that Northern Ireland is a particular subject of discussion, it is a legitimate point, is that there are particular circumstances in Northern Ireland at the border which deserve particular respect and sensitivity and that is what they have received," explained Mr Johnson.