Theresa May will face an open Tory rebellion that risks the collapse of her Government unless she delivers the Brexit "she herself has promised", Jacob Rees-Mogg has warned ahead of a critical summit at Chequers.

In a significant hardening of the position of Tory Eurosceptics, Mr Rees-Mogg made clear that he and his colleagues will vote against Mrs May's deal if she fails to "deliver what she has said she would".

Writing in The Telegraph, Mr Rees-Mogg compared Mrs May's position to that of Sir Robert Peel, the former Conservative Prime Minister forced to quit after his party revolted over the repeal of the Corn Laws.

It comes amid reports that the Prime Minister has told aides that she is prepared to stand and fight if Tory MPs force a vote to oust her, saying she will not be bullied out of office by hardened Eurosceptics.

Downing Street has reportedly produced a third model for handling customs after the UK leaves the EU.

Details of the new plan have not been revealed publicly, but ministers are expected to discuss it at Chequers on Friday.

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At least four Cabinet ministers - Sajid Javid, Michael Gove, Jeremy Hunt and Gavin Williamson - are said to be "on manoeuvres" and laying the ground for future leadership bids in the event that Mrs May should be forced to quit over Brexit.

On Friday the Prime Minister will host a meeting of her full cabinet at Chequers, her rural retreat, in a bid to thrash out difference over Britain's post-Brexit trade and customs arrangements, ahead of the expected publication of a white paper next week.

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Downing Street hopes it has now found its way out of a bind on customs, and a significant part of finding a solution to maintaining an open border with the Republic of Ireland, the BBC reports today.

Mr Rees-Mogg, who leads a 60-strong group of Tory Eurosceptic MPs, said that it is time for Mrs May and her Cabinet to decide whether to stand by her pledges on Brexit or reduce "a once proud country" to a "tremulous state that sees Brexit as mere damage limitation".

He said: "Theresa May must stand firm for what she herself has promised. One former Tory leader, Sir Robert Peel, decided to break his manifesto pledge and passed legislation with the majority of his party voting the other way. This left the Conservatives out of office for twenty-eight years.

"At least he did so for a policy that works. At Chequers the Prime Minister must stick to her righteous cause and deliver what she has said she would, she must use her undoubted grace to persevere."

The comparison to Sir Robert is particularly pointed, as the former Conservative Prime Minister was forced to resign in 1846 after his party revolted against his decision to repeal the Corn Laws. He was forced to rely on the Whigs and Radicals to repeal the laws, and resigned on the same day. He never held office again.

Mr Rees-Mogg warned that he and other Tory Eurosceptics will vote against the final Brexit deal if it crosses a series of red lines. They include enabling Brussels to impose laws "either directly or indirectly" on the UK after Brexit and inhibiting Britains ability to strike trade deals and control migration .

He also said that Theresa May's "idiotic" Customs Partnership plan, which Eurosceptic MPs fear could lead to a major climbdown over Brexit, must be ripped up.

"Any attempt by the EU to impose its laws and court on the UK, either directly or indirectly, must be rejected. Any EU agreement that restricts the country's ability to make trade agreements with other states, restricts our ability to control our migration policy makes us pay to trade or interferes with our fishing waters could not be accepted. Indeed MPs would vote against such propositions in Parliament."

His comments have drawn criticism from senior MPs. Sir Alan Duncan, a minister of state at the Foreign Office, accused Mr Rees-Mogg of "insolence" in "lecturing and threatening" the Prime Minister.

Mr Rees-Mogg said the Prime Minister made a "personal contract" with the British people when she declared that Britain will leave the single market and customs union.

He singled out Greg Clark, the Business Secretary who has suggested that the UK should join a single market for goods and financial services, for criticism.

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He said: "The Prime Minister said, as soon as she took office, that 'Brexit means Brexit' and in the last election, in her personal contract with the British people, she declared that we would leave the single market and customs union.

"At Chequers this week the nation will see if her promises are kept of if the policy advocated by a former member of the SDP [Greg Clark] wins favour."

The Cabinet must agree to withhold the £39billion Brexit divorce bill unless there is a firm guarantee of a trade deal before Britain leaves the EU.

Mr Rees-Mogg said that the failure to secure such a guarantee is "something I would strongly oppose in any vote in the House of Commons".

Greg Clark, Brexit Secretary credit: Getty Images

He said that leaving the EU "into the purgatory of a perpetual transition" would be foolish. It comes after Mr Clark, the pro-European Business Secretary, and Andrea Leadsom, the Eurosceptic Leader of the Commons, both suggested yesterday that the post-Brexit transition period could be extended beyond December 2020.

He said that "above all" the Cabinet must be clear that it is prepared to accept no-deal. "It must maintain the clear negotiating line set out at the beginning: no deal is better than a bad deal and plenty of bad deals are on offer," he says.

He also argued that it is time to "call Ireland's bluff" over the border issue, saying that there is "no insurmountable problem" and that "any solution which would split the UK in two is outrageous".

Mr Rees-Mogg is head of the European Research Group of Conservative MPs, which in recent weeks has been relatively restrained over Brexit.

However following the passing of the EU withdrawal bill last month it is now prepared to play a significantly more active role in the Brexit debate.

It came as Simon Stevens, the chief executive of the NHS, said that "significant" preparations for a no-deal Brexit are underway to ensure the continued flow of medical supplies.

Cabinet ministers on manoeuvres

At least four members of Theresa May's Cabinet are "on manoeuvres" and are actively preparing the ground for leadership campaigns if she is forced to quit, Tory MPs have said.

Michael Gove, Sajid Javid, Jeremy Hunt and Gavin Williamson are all said to have held wide-ranging discussions with colleagues in recent weeks which have been seen as an attempt to build alliances.

It comes amid mounting speculation that the Prime Minister will be forced to step down if she fails to broker a truce over Brexit this weekend at her rural retreat of Chequers.

Michael Gove

Michael Gove, the Environment Secretary credit: REUTERS

The Environment Secretary has already placed himself at the heart of the Government's domestic agenda with his war on single-use plastics such as disposable coffee cups.

He has made a series of wide-ranging speeches at think tanks, including one in which he declared war on "crony capitalists" who have "rigged the system" in their favour.

He also appeared at the launch of the Onward think tank alongside Ruth Davidson, the leader of the Scottish Conservatives, sparking suggestions they could form an alliance in a future leadership bid.

More recently Mr Gove is said to have joined colleagues in the members' dining room where he asked leading questions about the future of the Conservative Party, including a proposal to abolish HS2.

Sajid Javid

Sajid Javid, the Home Secretar credit: PA

Since his appointment as Home Secretary, Mr Javid has clashed with the Prime Minister over her hardline stance on migration.

He has already won a significant concession from the Prime Minister which will see thousands more visas issued to foreign doctors and nurses. He has also refused to back the Prime Minister's net migration target and suggested that foreign students should be stripped out of official figures.

A Cabinet source told The Sunday Times he has been inviting middle-ranking ministers from other departments for hour-long conversations. He has also doubled the size of his team of special advisers.

Jeremy Hunt

Jeremy Hunt, the Health Secretary

Having fended off a bid by Mrs May to move him on as Health Secretary, Mr Hunt has established himself as a firm Eurosceptic despite having backed Remain during the EU referendum.

He recently criticised Airbus after it said it threatened to pull investment from Britain, describing its intervention as "completely inappropriate" and urging the country to ignore "siren voices".

He is seen by some as a compromise candidate, and is said to have taken to inviting colleagues in groups of eight or 10 for meetings with sandwiches in Portcullis House.

He won a significant battle to secure £20billion a year in extra funding for the NHS, although he could face a backlash from Tory colleagues if it is funded by tax rises.

Gavin Williamson

Gavin Williamson, the Defence Secretary credit: AP

The Defence Secretary has been locked in an extraordinary row with the Prime Minister over defence funding, and has been accused of telling officials that he could bring her down. "I made her and I can break her," he is alleged to have said - although aides deny he used that form of words.

The former Chief Whip is said to visit the tearooms every morning, where he has been seen meeting with Eurosceptics MPs. Like Jeremy Hunt, Mr Williamson has become a keen Brexiteer himself. It comes amid suggestions that defence chiefs and ministers are planning to enlist the support of the Royal family to secure more defence funding.