Theresa May desperately attempts to salvage Brexit deal with 48 hours before critical Commons vote

One senior Conservative warns PM's position may become untenable if her Brexit policy is 'dismantled' in coming days

Theresa May has been warned she could be forced out of Downing Street if her Brexit strategy is dismantled by MPs this week in a series of critical votes.

As negotiations entered the eleventh hour, the prime minister was desperately attempting to salvage her withdrawal deal, with a plane reported to be on standby at RAF Northolt to fly her to Brussels at the first sign of EU officials shifting their position.

However, it remained unclear whether the prime minister would be making a dash to the Belgian capital, as hopes of achieving any significant concessions appeared to fade.

On Tuesday evening, MPs will once again vote on her Brexit deal. And without substantive changes to the contentious Irish backstop, it appears the prime minister’s deal will receive a potentially fatal blow.

Ms May’s first attempt was rejected by the Commons in January by 230 votes – the biggest defeat for a government in British political history.

If the prime minister loses again and her policy is “dismantled” by parliament in the coming days, her position could become untenable, warned the senior Conservative MP Nicky Morgan.

“I think it would be very difficult for the prime minister to stay in office for very much longer,” she said on Sunday.

Meanwhile, the foreign secretary Jeremy Hunt also warned there was a real risk for Brexiteers of “losing Brexit” in the coming weeks, as he admitted the “wind was in the sails” of pro-referendum campaigners.

In a pointed warning to colleagues planning to vote down the prime minister’s deal, he said that in three weeks’ time, activists could be two-thirds of the way to forcing a public vote.

Dominic Raab, who resigned as Brexit secretary last year over Ms May’s deal, said the government was in a “precarious” position ahead of the vote, which would “get even trickier” if MPs demand and get an Article 50 extension later this week.

Crucial to Ms May gaining the support of the hardline group of Brexiteers MPs in the European Research Group (ERG) will be the legal opinion of attorney general Geoffrey Cox.

The legal advice that Mr Cox presented to Ms May in November warned the UK was at risk of being trapped in the backstop indefinitely. He has been intimately involved in the negotiations in recent weeks.

“I am putting my hand on my heart,” he told the Mail on Sunday. “I will not change my opinion unless we have a text that shows the risk has been eliminated. I would not put my name on anything less.”

The deputy chair of the ERG, Steve Baker, and the Democratic Unionist Westminster leader Nigel Dodds said in a joint newspaper article that without concessions, defeat on Tuesday for the prime minister is “inevitable”.

“An unchanged withdrawal agreement will be defeated firmly by a sizeable proportion of Conservatives and the DUP if it is again presented to the Commons,” they wrote.

“If with the DUP just half of previous Conservative opponents vote against the deal, a three-figure majority would be expected.”

Another ex-Brexit secretary, David Davis, described the scenario of no Brexit at all as a “democratic disaster”, adding that “Britain will get its Trump moment” if parliament fails to deliver on the result of the 2016 referendum.

Both the shadow chancellor John McDonnell and shadow Brexit secretary Keir Starmer said Labour was focused on opposing the prime minister’s deal and that the push for a second referendum would follow in due course, but not this week.

The pair backed extending the Article 50 negotiating period, with Mr McDonnell suggesting any delay should be “as long as necessary” in an interview on the BBC’s Andrew Marr show.

Their comments came as two Labour MPs hoping to force a fresh public vote – Peter Kyle and Phil Wilson – said they would not be tabling their amendment on Tuesday.

Their plan suggests providing support for the prime minister to get her deal through the Commons on the condition of it then being put to the country in the form of a second referendum.

“It’s very much a rollercoaster – the focus is going to be on defeating the meaningful vote,” Mr Wilson told The Independent as he confirmed he was “postponing” the amendment for a future day.

He insisted there “will be other opportunities”, and said no matter what the deal is, the public have a right to decide in a confirmatory poll. “This a decision that is going to affect the country for years,” he said.

A senior Labour source also did not rule out the possibility of Mr Corbyn tabling a second motion of no confidence in the coming days in an attempt force a general election by capitalising on the expected turmoil at Westminster.

The Labour leader’s previous attempt – following the crushing defeat of Ms May’s agreement in January – was unsuccessful, as MPs voted by 325 to 306 to support the government.