THERESA May has admitted that she doesn’t know what will happen if Parliament rejects her Brexit deal when MPs get their meaningful vote on December 11.

The candid admission came in the House of Commons yesterday as the Prime Minister faced relentless criticism of the Withdrawal Agreement and Political Declaration she had negotiated with Brussels.

MPs from all parties urged her to back down, but May, despite facing almost certain defeat, refused to compromise, ruling out any attempt at renegotiation, a second referendum, or extending Article 50.

Her “ploughing on” with the little liked Withdrawal Agreement was not “stoic” but an “act of national self-harm,” Labour leader Jeremy Corbyn said.

Meanwhile, the SNP’s Ian Blackford told May her botched plan demonstrated the “real cost” of Scotland “not being an independent country able to take our own decisions”.

It was the third time in as many weeks that May came to the Commons in a bid to sell her Brexit deal.

Despite the EU27 signing off the package at a special summit on Sunday, May struggled to find support among the green benches. It was over an hour before an MP said anything positive.

She also lost the support of previously loyal MPs, with former defence secretary Sir Michael Fallon calling the agreement a “gamble”.

May told MPs: “We can back this deal, deliver on the vote of the referendum and move on to building a brighter future of opportunity and prosperity for all our people.

“Or this House can choose to reject this deal and go back to square one. Because no one knows what would happen if this deal doesn’t pass. It would open the door to more division and more uncertainty, with all the risks that will entail.”

The Tory leader also responded to comments from French president, Emmanuel Macron, where he seemed to suggest the UK could be trapped in the backstop if London refuses European boats access to British waters.

“The EU have maintained throughout this process that they want to link overall access to markets and access to fisheries,” May said. “They failed in the Withdrawal Agreement and they failed again in the Political Declaration. It is no surprise some are already trying to lay down markers again for the future relationship. They should be getting used to the answer by now: it is not going to happen.”

But Blackford was sceptical: “Here we are again with another sell-out of the Scottish fishing industry by a Tory Government. We have been here before: we were sold out by Ted Heath and we have been sold out repeatedly by Tory Governments.”

He said the agreed declaration “would almost certainly” leave the UK in the Common Fisheries Policy with “no voting rights for another one or two years”.

“The Prime Minister says the deal ends uncertainty. It does not end uncertainty for Scotland’s fishing sector or for the future state of the economy, which faces years of turbulence in a bureaucratic tangle,” he added.

And north of the Border, Scotland’s Brexit Secretary Michael Russell chipped in – stressing the damage the deal could have on the country.

He said: “This is a damaging deal for people in Scotland. By removing us from the EU and single market, which is eight times the size of the UK alone, this deal will hit the economy and living standards. Ending freedom of movement will make it harder to attract the staff we need for the NHS.

“Analysis of the deal demonstrates that this is a blindfold Brexit with major issues left unresolved. This means that far from providing certainty and bringing Brexit negotiations to an end, this deal will mean more years of negotiations and real economic uncertainty with no guarantee that an eventual trade deal can even be agreed.

“The Scottish Government will continue to work with others to achieve a better deal keeping Scotland and the UK inside the single market and customs union and we will continue to support another referendum on EU membership.”

But in her statement, May made clear that the plan would not be changed.

“I do not pretend that either we or the EU are entirely happy with these arrangements. And that’s how it must be – were either party entirely happy, that party would have no incentive to move on to the future relationship.

“But there is no alternative deal that honours our commitments to Northern Ireland which does not involve this insurance policy. And the EU would not have agreed any future partnership without it.”

In another unexpected admission, the Prime Minister said she should not have referred to EU citizens migrating to the UK as “queue jumpers”.

Raising it in the Commons, SNP MP Philippa Whitford, whose husband is German, said the comment had caused “insult and upset”.

May replied: “I should not have used that language in that speech. The point I was making is a simple one. Right from the very beginning, I have said that citizens’ rights is a key issue that I want to see addressed in the Withdrawal Agreement.”