- Video report by ITV News political editor Robert Peston
David Davis has backed Boris Johnson who delivered a scathing attack on Theresa May's Brexit strategy, telling ITV News: "We have to be tough with the Europeans."
The former Brexit secretary agreed with the ex-foreign secretary that the UK "needs to be stronger" in its negotiations with the EU, and that the Chequers plan "is not what we want".
In an article for The Daily Telegraph Mr Johnson branded the Prime Minister's Brexit strategy a “fix” that results in the UK gaining "diddly squat" when it "hands over £40 billion of taxpayers’ money", and will only lead to victory for the EU.
In what is likely to be seen by many at Westminster as the beginning of a bid to try and oust the Prime Minister, the ex-foreign secretary likened withdrawal talks as a rigged wrestling match where the UK is “lying flat on the canvas".
Downing Street has delivered a stinging slapdown to Mr Johnson, saying he has produced "no new ideas" on Brexit.
In a barely-veiled rebuff to Mr Johnson's ambitions to become prime minister, Mrs May's official spokesman told reporters that the country needed "serious leadership with a serious plan" which was being provided by the current premier.
But Mrs May's spokesman insisted that the Chequers proposals were "the only credible and negotiable plan which has been put forward".
And the spokesman added: "Boris Johnson resigned over Chequers. There's no new ideas in this article to respond to.
"What we need at this time is serious leadership with a serious plan and that's exactly what the country has with this Prime Minister and this Brexit plan."
Mr Davis said Mr Johnson "had a point" but refused to be drawn on a potential challenge to Mrs May's party leadership, adding: "It's not for me."
Mr Johnson said Britain has “gone into battle with the white flag fluttering over our leading tank” due to Mrs May’s Chequers proposals to align UK standards on goods to the EU.
Mr Davis, who resigned from his Cabinet position in July, said: "We have to be tough with the Europeans. We have to be more determined about it and we have to have a very clear idea of what we want. Chequers is not what we want, it doesn't meet the promises. What we need is a free trade plus deal and that's what we should be pushing for."
He added that it was likely that the Europeans would turn down the Chequers proposals "or add so much to it, it's unacceptable" and that it was unlikely to get through parliament.
He said: "We should start thinking about our alternative strategy right now and putting it in place right now."
The comments came after Mr Davis told the BBC's Andrew Marr that the Chequers blueprint was “actually almost worse than being in” the EU.
Mr Johnson compared withdrawal negotiations between Brexit Secretary Dominic Raab and the EU’s Michel Barnier to a fixed wrestling match.
Writing in the Daily Telegraph, Mr Johnson said: “Out of their corners come Dominic Raab and Michel Barnier, shrugging their shoulders and beating their chests – and I just hope you aren’t one of those trusting souls who still thinks it could really go either way.
“The fix is in. The whole thing is about as pre-ordained as a bout between Giant Haystacks and Big Daddy; and in this case, I am afraid, the inevitable outcome is a victory for the EU, with the UK lying flat on the canvas and 12 stars circling symbolically over our semi-conscious head.”
Labour leader Jeremy Corbyn said: "It sounds like it is and it sounds like Boris Johnson, having spent two years as Foreign Secretary, has achieved nothing and now says it's all off.
"Well surely, it's time for some serious people to take over the negotiations? The Tories have had two years since the referendum and made no progress at all."
Mr Johnson accused “some members” of the Government of deliberately using the Irish border situation to “stop a proper Brexit” and effectively keep Britain in the EU.
He said that the real “scandal” was “not that we have failed, but that we have not even tried” on Brexit.
The intervention comes as Mrs May faces growing opposition on Tory benches to the Chequers Cabinet compromise on the Brexit strategy which triggered the resignation from the Government of Mr Johnson.
With Parliament returning from recess on Tuesday, the PM is expected to face a coordinated effort from Tory hardline Brexiteers to abandon her exit agenda amid reports that election strategist Sir Lynton Crosby is involved in a “chuck Chequers” campaign.
Mr Barnier has stated he “strongly opposed” the Chequers proposals because such “cherry-picking” would mean the end of the European project if enacted.
Mr Johnson said: “They may puff about ‘cherry-picking’ the single market. There may be some confected groaning and twanging of leotards when it comes to the discussion on free movement. But the reality is that in this negotiation the EU has so far taken every important trick.
“The UK has agreed to hand over £40 billion of taxpayers’ money for two thirds of diddly squat.
“We will remain in the EU taxi; but this time locked in the boot, with absolutely no say on the destination. We won’t have taken back control – we will have lost control.”
In another sign of Cabinet tensions, International Development Secretary Liam Fox took a swipe at the Treasury over gloomy predictions on the consequences of a no-deal scenario.
Dr Fox told the BBC: “Can you think back in all your time in politics where the Treasury have made predictions that were correct 15 years out, I can’t, they didn’t predict the financial crisis that happened, no-one could.
“So this idea that we can predict what our borrowing would be 15 years in advance is just a bit hard to swallow.
“To say what a GDP figure would be 15 years ahead is not a predictive power that I’ve known the Treasury to have in my time in politics … I don’t believe it is possible to have a 15-year time horizon on predictions on GDP.”