Ministers believe the Government will be unable to stop Parliament forcing the UK to stay in a customs union in a move which will strip away the benefits of Brexit and force a long delay to departure. It comes as at least 170 Tory MPs – two thirds of the parliamentary party – have signed a letter telling Theresa May she has to take Britain out of the European Union within weeks even if it means leaving with no deal. The letter, authored by Brexit minister Chris Heaton-Harris, has been signed by at least 10 cabinet ministers and comes as fed-up Conservative MPs have indicated they are prepared to bring down her Government if she does not deliver Brexit.
There may be some jiggery pokery to try to get round them but it will be very hard to ignore the will of Parliament
Despite this latest blow to her authority, Mrs May has let it be known that she will refuse to go through with a pledge to quit unless she gets her deal through Parliament on a possible fourth attempt next week.
In what could be a red letter day in Parliament tomorrow, former Tory minister Oliver Letwin, a leading Remainer, is set to bring forward so-called indicative votes again allowing MPs to try to find a preferred option.
Mr Letwin is set to be aided by Speaker John Bercow who has faced fierce criticism for abandoning his neutrality and consistently trying to allow Parliament’s Remainer majority to thwart Brexit.
A senior cabinet source told the Sunday Express: “We are not sure yet but there is a chance that these votes could be legally binding.
“There may be some jiggery pokery to try to get round them but it will be very hard to ignore the will of Parliament.”
At least 170 Tory MPs have signed a letter directed to Theresa May
Another senior Government source added: “While Monday’s vote is indicative it is likely that it will be brought back for legislation on Wednesday.
“We have an activist Speaker who we can guess will allow Parliament to take control of this process.
“So Brexiteers have to realise that time and numbers are against them. We are in a Remainer trap. There is a big Remainer majority in Parliament and they will not get no deal but Parliament can in effect get a customs union agreement.
“That means we cannot have free trade deals with the rest of the world, we will have to accept freedom of movement and all the reasons people voted for Brexit will be lost.”
Sources close to Mrs May say that she will try to bring back her deal for a fourth time if the Speaker allows it.
A cabinet minister told this newspaper that colleagues demanding no deal are “living in cloud cuckoo land.”
Oliver Letwin is set to bring forward indicative votes again
The senior minister said: “We are just not ready for no deal. We are not even close, it would be a disaster.”
A source close to the Prime Minister added that her promise to quit as leader at the meeting of Tory MPs last week is “completely conditional on her deal being passed.”
Failing that she plans to stay on until at least November when Conservative MPs can hold another vote of confidence in her leadership to trigger a contest.
The customs union threats infuriated Tory MPs who warned that Mrs May risks the collapse of her Government.
Jacob Rees-Mogg, who reluctantly joined Boris Johnson and Dominic Raab in voting for the deal on Friday, said: “Downing Street could stop it [a customs union] if it had any gumption but does not, so will not.”
Two ministers have told this newspaper they would resign under these circumstances.
Jacob Rees-Mogg said Downing Street won’t stop a customs union
Former Brexit minister David Jones said: “For a customs union bill to pass into law there would need to be a money resolution which can only be introduced by the Government and cannot be introduced by a backbencher.
“So it would be a positive choice by the Prime Minister, not something she could not control.
“I personally would not vote with Labour to bring down the Government but I know many of my colleagues have said they would.”
Veteran Tory MP Peter Bone said: “The idea that the Government is powerless in this situation is ridiculous.
“The Prime Minister needs to carry out the promises we made in the manifesto and leave the EU either through a deal or a no deal.”
North West Leicestershire MP Andrew Bridgen, one of the 170 MPs to sign the letter, said: “She [Mrs May] has got to go.
“The party and parliament cannot carry on like this.
Peter Bone told Theresa May to ‘carry out the promises we made in the manifesto’
“But it’s clear to me, and I think it’s clear to most people in the country, whether you’re a Leaver or Remainer, that the European Union were never going to offer us a deal that is acceptable.
“To deliver on the mandate we’ve been given, to leave the EU, we have to leave without a deal.
“It’s obvious this customs union line is an attempt to bully MPs into backing the Prime Minister’s bad deal.”
Another Conservative MP said: “If she tries to stay on colleagues will literally go on strike. The Government won’t be able to get any business through.”
Another added: “The only thing she can threaten is to withdraw the whip but a lot of us are beyond caring about that.
“When you have cabinet ministers keeping their jobs after voting against the Government then what is the point of the party whip.”
Boris Johnson has been backed to run for the Conservative Party leadership
The revelation that Mrs May will not quit if she does not get her deal through will also come as a blow to a number of senior Tories who have started their leadership campaigns to replace her.
It is understood that in the cabinet Sajid Javid, Jeremy Hunt, Penny Mordaunt, Matt Hancock, Andrea Leadsom, Liz Truss and Gavin Williamson all have leadership teams.
Mr Williamson, the defence secretary has been taking MPs up in his plane to persuade them to back him, according to sources.
Meanwhile outside the cabinet Boris Johnson, Dominic Raab, Priti Patel, James Cleverly, Kit Malthouse and Tom Tugendhat are all being discussed as contenders.
Writing in the Sunday Express today Mr Cleverly has urged MPs to stop looking for “no change or perfection” with Brexit but to look beyond the issue to address what sort of country the party wants Britain to be.
Meanwhile, Mrs Patel, who on Friday became the banner bearer of the no deal opponents to Mrs May’s deal, has urged the party to adopt a vision where Britain can become “a beacon of free global trade.”