Brexit could be delayed if MPs fail to approve Theresa May’s deal, a government minister has admitted publicly for the first time.

Digital minister Margot James said that the UK may be forced into asking to extend the two-year ‘Article 50’ process for quitting the EU, should Parliament remain deadlocked.

Pro-EU campaigners pounced on her words, which came as Brexit Secretary Steve Barclay repeatedly refused to rule out the idea of an extension to the process.

Barclay said only that it was the “firm intention” of the government to ensure Brexit took place on March 29 as planned, a line echoed by No.10.

With just over a week to a crunch Commons vote on her plans, the PM hosted scores of Tory backbenchers for a Downing Street drinks reception as part of a New Year ‘charm offensive’ to woo support.

HuffPost UK understands that one key idea being pushed is for Brussels to agree a form of words making clear a future UK-EU trade deal would start in 2021, effectively putting a time limit on the controversial ‘backstop’ plan that so worries many Conservatives and the DUP.

And in a further bid to avoid a fresh row, the Treasury appeared relaxed about allowing a cross-party amendment to the Budget that would deny the Chancellor tax-changing powers in any no-deal Brexit scenario. 

Anti-Brexit MPs believe that delaying the process by a few months could give vital breathing space to get a different deal, or even to trigger a second referendum.

James told BBC2’s Politics Live programme that Britain “cannot afford” a no-deal exit that would occur if MPs failed to hammer out any agreement in coming weeks.

“The only way is for MPs to coalesce around a reasonable deal, which this is, and get it through. That is how you stop no-deal.

“If that proves to be impossible then I think we need to…we have very little time left but we might have to extend Article 50.

“But I think it is very unlikely that parliament will stare down the barrel of that particular gun.”

James’s words appeared to represent the starkest threat yet to Tory MPs that if they fail to back the PM then they risk losing Brexit itself.

Scottish Secretary David Mundell made a similar private warning in Cabinet late last year but until now no minister has gone public.

Later in the Commons, Brexit Secretary Barclay refused to give a categoric promise that Article 50 would not be extended.

Instead he pointed out that there were several obstacles to extending the Brexit talks period. 

“In terms of extending Article 50 the reality is it’s not a unilateral decision. That would require the consent of the other 27 member states,” he said.

“That would also raise all sorts of practical issues not least the [European] Parliamentary elections at the end of May. It is this government’s firm intention not to extend Article 50 and to leave the European Union.”

Asked about any extension, the Prime Minister’s official spokesman also said: “The PM has been very clear on a number of occasions that that is not something we are intending to do.”

In the Commons, Tory MP Julian Lewis pointed out that May had told MPs on 74 occasions that the UK will be leaving the EU “on 29 March” 2019. “Will the secretary of state confirm that under no circumstances will that date be postponed?,” he asked.

Barclay replied: “The Prime Minister has made that commitment crystal clear.”

But anti-Brexit MPs pounced on James’ remarks, claiming she had let slip the reality facing ministers.

Labour’s Owen Smith, part of the pro-EU ‘Best for Britain’ campaign, told HuffPost UK: “She’s right to say we may have to extend Article 50 when Parliament rejects this rubbish deal next week.

“But there’s little point in extending if all we are going to do is seek another tweak or twiddle to the Withdrawal Agreement.

“What we really need is some decisive action: the PM should put her shoddy deal to the country and ask people if they want Brexit now they know what it looks like or whether they’d rather stick with the safety and security of partnership in the EU.”

Some of the PM’s allies are still confident she can win round sceptical MPs if Brussels agrees next week a new clarification that a trade deal is expected to start in 2021.

Earlier, former Treasury permanent secretary Nick Macpherson tweeted that it was unrealistic to expect such a timeframe.

When his claim was raised by Lib Dem MP Vera Hobhouse, Barclay said: “I don’t agree with that estimate, we start from a position of equivalence, we are looking to put in place an agreement based on shared values.”

Meanwhile, Labour’s frontbench and more Tory backbenchers gave their support for the first time to a new amendment tabled by Yvette Cooper and Nicky Morgan to prevent a no-deal Brexit. 

But Treasury sources suggested that the amendment – to refuse some tax changes in a no-deal scenario – could be accepted.

Cooper told HuffPost UK: “If the Government won’t rule out No Deal then Parliament has to step in.

“This amendment is the first opportunity for MPs to insert safeguards into legislation to make it harder for the Government to push through a no-deal Brexit without Parliament’s agreement.”

Late on Monday, several MPs left the No.10 drinks reception but none appeared to have change their minds on May’s plans.

The DUP’s Nigel Dodds told BBC’s Newsnight it was ‘more a social occasion’ than a political one. He added that everyone would have to ‘wait and see’ whether the EU delivered on what No.10 were promsing.