Former Brexit secretary David Davis has warned of “dire” consequences for Conservatives at the next general election if the Government sticks to its negotiating stance on EU withdrawal.

In a letter to fellow Tory MPs, Mr Davis said a deal based on Theresa May’s Chequers plan would deliver “none of the benefits of Brexit” and reduce the UK to being “a rule-taker from Brussels”.

Mr Davis said that if a deal of this kind is struck, it will be “very obvious” to voters at the next general election that the Government had broken promises from the 2017 Conservative manifesto and the Prime Minister’s Lancaster House speech setting out her Brexit “red lines”.

He repeated his call for the Cabinet to ditch the Chequers plan, which envisages a free trade area for goods based on a “common rulebook”, and go for a looser free trade agreement like the Ceta deal between the EU and Canada.

In his letter, obtained by The Sun, Mr Davis said that the EU was likely either to reject the Chequers proposals at next week’s crunch summit in Brussels, or to demand “further significant concessions”.

But he said a “Canada-plus-plus-plus” deal was “within our grasp with political will and imagination”.

And he told fellow MPs: “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 deliver on a number of promises in the manifesto and in the Lancaster House speech.

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

“The electoral consequences could be dire.

“So it is in both the party’s interest, and crucially the national interest, that we reset our negotiating strategy immediately and deliver a Brexit that meets the demands of the referendum and the interests of the British people.”

He cautioned Mrs May against using “preposterous threats” that a refusal by Tory MPs to back Chequers could result in Brexit being lost altogether or watered down in order to get it through Parliament on the back of Labour votes.

Mr Davis’s letter came after Prime Minister was warned that she faces a Commons rebellion of at least 40 Conservative MPs if she returns from Brussels with a deal based on her Chequers plan, leaving the UK “half in, half out” of the EU.

Former Brexit minister Steve Baker told BBC Radio 4’s Today programme that as many as 80 Tories are ready to oppose the plan agreed by Cabinet at Mrs May’s country residence in July, adding: “The 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 the customs union, come what may.”

Meanwhile, Mrs May told her Cabinet that Britain will not accept an EU withdrawal deal without a “precise” political declaration setting out how its requirements on trade and security will be delivered.

Despite optimistic comments from senior EU figures about the prospect of progress at the October 17-18 European Council summit, the PM made clear that agreement has not yet been reached on key issues including the Irish border.

DUP leader Arlene Foster, whose MPs prop up the minority Conservative administration in the Commons, closed down one mooted avenue for compromise by insisting her party will not accept customs or regulatory checks on goods travelling in either direction between Northern Ireland and Great Britain.

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A DUP delegation led by Arlene Foster met EU chief negotiator Michel Barnier in Brussels (Arlene Foster/PA)

Reports had suggested that deadlock over the so-called “backstop” arrangements for Ireland could be broken by permitting checks on exports from the mainland to the north, but not in the opposite direction.

“There cannot be any customs or regulatory barriers between ourselves and the rest of the United Kingdom, both ways,” said Mrs Foster following talks with EU chief negotiator Michel Barnier in Brussels.

“It’s not just a case of regulations between Northern Ireland and GB, it’s also between GB and Northern Ireland. We’ve made that very clear.

“The Prime Minister understands our position and I expect her to respect that position.”

Mrs May told the regular weekly Cabinet meeting at 10 Downing Street that talks to finalise a withdrawal deal were continuing “on an intensive basis”.

Her official spokesman said: “She made clear that we can’t agreed to a withdrawal agreement without a precise future framework which delivers the future trade and security partnership which the Government wants.

“The PM said the UK would continue working hard in the talks on Brexit and the message from EU leaders is that they want to reach a deal.”

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(PA Graphics)

International Development Secretary Penny Mordaunt, who campaigned for Leave in the referendum, said Mrs May “has my support and I am not in any way expecting that situation to change”.

But she suggested that the Prime Minister may have to amend her Chequers plan to get a final deal, saying that “we don’t know where this is going to end up”.

The Prime Minister’s official spokesman said: “A Canada-style deal for the entire United Kingdom is not on offer from the European Union.

“What is on offer is a free trade agreement which covers Great Britain only.

“Northern Ireland would be kept inside the customs union and parts of the single market, effectively dividing the United Kingdom in two.

“As the Prime Minister and many others have said, that is unacceptable.”