Former Brexit minister Steve Baker has said up to 80 Tory MPs are considering voting against the Prime Minister’s “half-in-half-out Chequers [Brexit] deal”.

The prominent Brexiteer said that at least 40 MPs would vote down Theresa May’s deal, even after “every possible technique” is used by the Government to persuade or force MPs to toe the party line.

His claim comes as his former boss David Davis, who resigned at the same time, writes to Tory MPs warning of “dire” electoral consequences if May continues to pursue a Chequers plan.

“If we stay on our current trajectory we will go into the next election with the government having delivered none of the benefits of Brexit, with the country reduced to being a rule-taker from Brussels, and having failed to deal with a number of promises in the manifesto and the Lancaster House speech,” he said.

“This will not be a technicality, it will be very obvious to the electorate”.

On BBC Radio 4’s Today programme earlier on Tuesday, the host asked Mr Baker: “So you are sticking by the assessment that you have 80 MPs that are prepared to vote against the Prime Minister on a Brexit deal based on Chequers?”

Mr Baker replied: “I did a concrete canvas of colleagues when it was amendments to legislation and came up with the number nearly 80.

“Of course, the Government are going to whip this vote extremely hard but what I would say is, whips would be doing incredibly well if they were to halve the numbers.

“My estimate is that there are at least 40 colleagues who are not going to accept a half-in, half-out Chequers deal. Or indeed a backstop that leaves us in the internal market and customs union come what may.”

Mrs May has said a “no deal” would be better than a free trade deal favoured by the Brexiteer European Research Group led by Jacob Rees-Mogg, claiming her plan is the only option.

Reports this Tuesday claimed Mrs May’s government is now planning a new wave of “project fear” to push MPs into voting for her Chequers plan, despite it being unpopular with the public, and many Remainer and Leave MPs.

Mr Baker, who resigned as Brexit minister over the Chequers plan, added: “I don’t doubt that every possible technique is going to be used to sew doubt in colleagues’ minds to encourage them to vote with the Government.

“In the end, the EU is not entitled to split the UK and it is not entitled to constrain how we regulate the economy and how we govern ourselves after we leave.

“If the UK faces either possibility then we must, in the end, be willing to say that it is a bad deal and no deal is better than a bad deal, it has been said before many times.

“And therefore we must be unafraid to go forward without an agreement.”