ES News email The latest headlines in your inbox twice a day Monday - Friday plus breaking news updates Enter your email address Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid You already have an account. Please log in Register with your social account or click here to log in I would like to receive lunchtime headlines Monday - Friday plus breaking news alerts, by email Update newsletter preferences

Theresa May was threatened with a snap general election today if she is defeated by Parliament on her Brexit deal.

Tory right wingers raised the “nuclear threat” of a forced election in what was seen as an attempt to see off calls to empower the Commons to amend the deal or call for fresh negotiations.

Iain Duncan Smith, the former Conservative leader and leading Brexit-backer, said it would be on “a confidence issue” and defeat would make the Government “head towards” a general election.

“It will be the most important vote of the entire Parliament and if the Government loses it you head towards that conclusion,” he told the Evening Standard.

Mrs May is aiming to hammer out a leaving deal with the EU by October or November next year.

The decision on whether Parliament gets a “take it or leave it” vote or the right to amend the deal is shaping up to be the key battle of Brexit.

John Whittingdale, the former Culture Secretary, claimed the vote itself would be “a vote of confidence in government” that would trigger an election if defeated.

“I think for the Government to come to Parliament and say we have a deal ... and for Parliament then to turn around and say, ‘well, actually, we don’t agree it’s a good deal and we’re going to throw it out’, that is a vote of confidence in government,” he told The Westminster Hour.

“I can’t see how the government could say ‘oh alright then, we’ll go and have another go’. I think there would have to be a general election.”

But MPs backing a softer pro-business Brexit said Mrs May must keep Parliament involved.

Nicky Morgan, the chair of the Treasury Select Committee, said: “Ministers have promised Parliament a meaningful vote. They need to keep Parliament informed and involved to avoid problems at the end.

“They resisted a Parliamentary vote on Article 50 until compelled to give way. They should do all they can to avoid a repetition.”

Former minister Bob Neill said the eurosceptic threat smacked of “desperation”.

He said: “They are certainly trying to set up a deliberate scare story because they know that there is no majority for their kind of hard Brexit in the Commons.”

He added: “They have selective memories. As Maastricht rebels not only did they vote regularly against their own government, but having defeated it on the Treaty one day, they would vote for it on a confidence motion the next. Don’t think they should threaten or preach at any one.”