His departure comes days after Theresa May secured the cabinet’s backing for her Brexit plan despite claims from critics that it was “soft”.
Mr Davis was appointed to the post in 2016 and was responsible for negotiating the UK’s EU withdrawal.
Junior minister Steven Baker quit shortly after Mr Davis – as Mrs May prepares to face MPs and peers later.Boris Johnson is probably weighing up which side is likely to win before choosing where he stands.
In his resignation letter, Mr Davis told Mrs May
“the current trend of policy and tactics” was making it “look less and less likely” that the UK would leave the customs union and single market.
He said he was “unpersuaded” that the government’s negotiating approach “will not just lead to further demands for concessions” from Brussels.
Mr Davis said:
“The general direction of policy will leave us in at best a weak negotiating position, and possibly an inescapable one.”
In her reply, Mrs May said: “I do not agree with your characterisation of the policy we agreed at Cabinet on Friday.”
She said she was “sorry” he was leaving but would “like to thank you warmly for everything you have done… to shape our departure from the EU”.
According to the Guardian
Theresa May will now have to confront furious pro-Brexit MPs in parliament on Monday, knowing she has lost the backing of one of the leaversâ€™ champions in government.
The prime minister is facing a growing backlash from the pro-Brexit wing of her party, with MPs warning they are prepared to trigger a leadership contest.
If at least 48 MPs send letters to Sir Graham Brady, chair of the powerful backbench 1922 committee, he would have to call a vote of no confidence â€“ though many of Mayâ€™s supporters in the parliamentary party believe she could win it.
Davis had clashed with May on several occasions in recent weeks, including over when the long-awaited white paper setting out the governmentâ€™s Brexit position should be published.
He would prefer a much looser, Canada-style relationship with the EU27 after Brexit â€” a proposal rejected by the cabinet on Friday.
In her reply to Davisâ€™s resignation letter, the prime minister emphasised he had quit â€œwhen we are only eight months from the date set in lawâ€� for the UK to leave the EU. She rejected his characterisation that the policy agreed at Chequers on Friday would not bring powers back from Brussels to Britain.
Mrs May future looks shaky but a leadership challenge will surely satisfy no one,
The Hard Brexiters Ress Mogg. Peter Bone and Boris Johnson will not accept anyone who does not come from within their ranks, but do they have enough numbers to win a leadership contest?
Would those Remainers in the Conservative party who support the single market, even Mrs May’s weekend hotchpotch seriously want to be led bu some kind of English Nationalist Brexiter who wants to cut the UK from Europe entirely?
What will this have on the leadership battle for the leadership of the Conservatives in the Welsh Assembly?
The two declared candidates Paul Davies and Suzy Davies do not have much difference between them and I believe both voted for remain.
Could they take now take opposite sides either for political advantage or less likely conviction/
and what of Labour? Leader Jeremy Corbyn is as a Hard Brexiter as as Rees Mogg , how much longer is he going to oppose not only the wishes of his MP’s and party members but more importantly Labour voters.
The whole Brexit Edifice is collapsing around us, and the outcome is far beyond clear.