MICHAEL Gove has insisted Theresa May’s Chequers plan offers “a proper Brexit” as he urged Conservative colleagues to “get behind” the embattled Prime Minister.

The Environment Secretary, who was a leading light in the Leave campaign, accepted that Friday’s agreement was not everything the Brexiteers had wanted but stressed it was a “perfect balance” between sharing regulations on 20 per cent of the UK economy - a “common market of goods” - with the EU but being outside the bloc’s remit on 80 per cent of it ie services.

Asked if the Chequers deal was everything he had personally hoped for, the Scot told the 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.

“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."

Mr Gove rebuffed the suggestion by his Cabinet colleague and fellow Brexiteer Boris Johnson that selling Mrs May’s compromise would be like “polishing a t***”.

He denied the Chequers deal offered “fake sovereignty” or that it would plunge Britain into a “Brexit black hole” and stressed that from now on “collective responsibility reigns”.

The Secretary of State also warned Brussels not to be inflexible in its response, saying if it continued to be so, then Britain would “walk out” of the talks.

The PM, who tomorrow is due to make a Commons statement on her compromise deal and will later address Tory MPs at a potentially fractious meeting of the party’s 1922 backbench committee, is said to be facing a potential leadership challenge with right-wing critics accusing her of “complete capitulation” to Brussels.

Some 48 signatures from Conservative MPs are needed to spark an automatic leadership contest.

Tory backbencher Andrew Bridgen expressed his unhappiness with Mrs May’s compromise by declaring he would not back it "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."

Yet, despite the offer "crossing many of the supposed red lines" outlined by the PM, the Leicestershire MP, when asked about a demand for a confidence vote in his leader, said: "We're not there yet."

Earlier, he wrote Jacob Rees-Mogg, who leads the pro-Brexit European Research Group, was now the only credible challenger to Mrs May after the failure by Cabinet ministers to oppose the Chequers plan.

Veteran Tory Eurosceptic Sir Bill Cash was also keen not to rush into challenging Mrs May’s leadership and said he would wait for the detail in the White Paper, which is due to be published later this week.

The Staffordshire MP 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."

Sir Bill 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 and as a matter of fact nobody can stop them, once the decision has been taken by those people the chairman of the 1922 Committee has to implement the process."

Meanwhile, the Labour leadership branded the Chequers deal "unworkable" and a "fudge" and challenged the PM to put it to a Commons vote.

Sir Keir Starmer described Mrs May’s compromise as a "bureaucratic nightmare".

He told the Marr Show: "I'm afraid it's got fudge written all over it.

"If you look at the facilitated customs arrangement, the sort of heart of this, it's a rebadging of the partnership and it's based on the idea that at the border you can distinguish between goods that are going to stay in the UK and those going to the EU.

"It's unworkable, it's a bureaucratic nightmare, so this a fudge," declared the Shadow Brexit Secretary.

The Labour frontbencher called for MPs to be given the chance to vote between Labour and the Government's customs plans.

"We've now got two propositions, we've got the Labour proposition, which has the majority support in Parliament, and the Prime Minister's new proposition, let's put it to a vote. I challenge the Prime Minister: put it to a vote and see where the majority is in Parliament on a customs union," added Sir Keir.

His Labour colleague, Hilary Benn, who chairs the Commons Brexit Committee, said he believed the transition period would have to be extended under the Chequers agreement.

Asked if more time would be needed to negotiate a deal with the EU, he replied: "It’s definitely more likely the transitional period is going to have to be extended because the Government itself now admits that now with this latest version, this facilitated customs arrangement; it isn't going to be ready by the end of the current proposed transition period which is December 2020."

He added that if the plans did not work out, then the Government should "bite the bullet and say remaining in the customs union is much the simplest and easiest way of doing this".

Justine Greening, the former Education Secretary, said Mrs May’s compromise was "sensible" and called on her colleagues to stop arguing.

“My sense is that we now really need to stick together as a party, get behind the Prime Minister and try and make sure that we support her as she goes through what are going to be monumentally difficult negotiations with the EU."

She added: "The time for arguments within that Chequers team, within that Cabinet team, has now got to stop."

Elsewhere, Gerard Batten, the Ukip leader, said the Chequers deal was a “betrayal” of the referendum vote.

"May has done everything she possibly can in the past two years to delay Brexit, to impede Brexit, and all in the intended outcome of reversing the referendum decision.

"The Chequers agreement is the opposite of what Mrs May promised us two years ago, when she said the UK wouldn't be half-in and half-out of the EU.

"With this agreement, we are more in than we are out and means the UK will have a similar status to those countries applying to join the EU.

"The implications of that is obvious. It would seem to me that Mrs May hopes that by getting rid of the Ukip MEPs next March the party will disappear from the political scene."

But he added: "This agreement betrays the referendum result and shows exactly why Ukip needs to become stronger than ever."