Theresa May has been warned by Cabinet ministers she will have to quit if her Brexit deal is defeated in the Commons next week and she fails to secure better terms from the EU, the Telegraph can disclose.

Ministers believe that there is “zero” chance of her deal, which has been publicly criticised by more than 100 Tory MPs, passing in a crunch Commons vote on Tuesday.

One Cabinet minister told the Telegraph “she [Mrs May] will fall” if she is defeated and then fails to go back to Brussels to fundamentally renegotiate the EU withdrawal agreement.

It came as Iain Duncan Smith, a Eurosceptic Tory MP and former Conservative leader, warned for the first time that Mrs May could have to go if she and her Cabinet decide to “brazen it out” in the wake of the vote.

He told the Telegraph: “How the PM responds after the vote matters more than anything else she has done. I believe that if the response is we’ve lost but we will do this all over again it will become a leadership issue.