Foreign Secretary Boris Johnson has strongly criticised the Prime Minister's Brexit plans using some colourful language, according to reports.
Mr Johnson is reported to have repeatedly described the backing the plan, which will see the UK tied to EU rules on goods, as like "polishing a turd".
All members of the Cabinet have signed up to the proposals, which were the subject of lengthy discussions at Chequers on Friday.
On Saturday, the prime minister told ITV News Political Editor Robert Peston that it was "clear" at the cabinet meeting there was a "feeling of collective responsibility" to sell the plan to the EU as she called for an end to dissent.
Brexiteer Cabinet minister Michael Gove admitted the plan was not everything he had hoped for but he was a "realist" and the Prime Minister's lack of a Commons majority meant the "parliamentary arithmetic" was a factor in deciding what could be adopted.
Mr Gove said the Prime Minister "allowed us, during the course of a day, to share views, to share analyses and to look at this proposal in detail but at the end of it collective responsibility reigns".
Mr Gove said the compromise plan was a "perfect balance" between the need for close access to Europe and the ability for the services industry to diverge.
Asked if it was everything he hoped for, Mr Gove told BBC's Andrew Marr Show: "No, but then I'm a realist and one of the things about politics is you mustn't, you shouldn't make the perfect the enemy of the good. One of the things about this compromise is that it unites the Cabinet."
He added: “All those of us who believe that we want to execute a proper Brexit, and one that is the best deal for Britain, have an opportunity now to get behind the Prime Minister in order to negotiate that deal.”
It was now up to the European Union to show flexibility in the negotiations – with the UK Government stepping up preparations to show that it can walk away from talks without a deal if necessary, he said.
“We will be in a position in March 2019, if we don’t get the deal we want, to be able to walk away,” he said.
The Prime Minister faces a potentially stormy meeting with Tory MPs on Monday evening, with reports that letters calling for a leadership contest have been submitted to the backbench 1922 Committee.
Veteran Tory Eurosceptic Sir Bill Cash told Sky News: “There are a lot of questions in here, there is a lot of unhappiness, there is a great deal of concern that we are saying that we leave – it’s not ‘to be or not to be’ it’s ‘to leave or not to leave’.
“The question is how do you leave and is this going to be a proper Brexit? There will be a massive discussion about all this.”
He said he had not written a letter calling for a leadership contest but “if people were to decide to put in those letters you only need 48”.
Tory backbencher Andrew Bridgen said he wouldn’t back the deal even “if the EU were paying us”.
He told BBC Radio 5 Live’s Pienaar’s Politics: “I’m very, very disappointed with the offer that we’ve seen coming out of Chequers – I’m disappointed that so-called Brexiteers in the Cabinet didn’t pick up the cudgels and fight for a better offer.”
The plan “crosses many of the supposed red lines” outlined by the Prime Minister, but said “we’re not there yet” when asked if he would be demanding a vote of confidence in Mrs May.
Mr Bridgen, writing in the Mail on Sunday, also aid Jacob Rees-Mogg – leader of the pro-Brexit European Research Group (ERG) – was now the only credible challenger to Mrs May after the failure by Cabinet ministers to oppose the Chequers plan.
Efforts to build support for the plan will see MPs invited to attend presentations organised by Chief Whip Julian Smith and Mrs May’s chief of staff Gavin Barwell.
Mr Gove was not the only Cabinet minister trying to win over critics.
A joint column written by Chancellor Philip Hammond and Transport Secretary Chris Grayling in the Sunday Telegraph said: “What was agreed at Chequers on Friday night is a pragmatic as well as a principled Brexit deal, one that works for both the EU and the UK.”
But former Tory leader Iain Duncan Smith told the Sunday Telegraph the Chequers plan appeared to amount to “continued membership” of the customs union and single market for goods despite the Prime Minister’s promise to leave both.
“If the public perceive that not to be delivered then the Government, I’m afraid, will suffer the consequences at the next election,” he said.
An analysis of the Chequers statement circulating within the ERG was damning about the plans.
The Chequers proposals “lead directly to a worst-of-all-worlds ‘black hole’ Brexit where the UK is stuck permanently as a vassal state in the EU’s legal and regulatory tarpit”, the briefing by Martin Howe QC concluded.
The document has not been endorsed by the ERG but was “devastating”, a Brexiteer source said.