Prime Minister Theresa May’s government was thrown into turmoil late Sunday with the surprise resignation of David Davis, her “Brexit minister” in charge of negotiating Britain’s exit from the European Union.

The midnight resignation came as a shock to British politics, exposing May to challenge by Conservative party members outraged over what they see as her plan to secure a “soft Brexit” that keeps Britain tied to many rules and regulations of the European Union after it leaves the bloc next year.

Hardline Brexit backers who argue that May should have a clean, decisive break from Brussels, spent the weekend complaining that her recently revealed proposals were a timid capitulation, a “Brexit in name only,” that ignored “the will of the people” who voted 52 to 48 percent in June 2016 to leave the European bloc.

In his letter of resignation, Davis told May that her tactics and proposals make it “look less and less likely” that Britain would leave Europe’s single market and customs unions -- two promises May has made. Davis said the government’s approach will just lead to further demands from Brussels and will give Europe control of large swaths of the British economy.

The prime minister’s plan for a soft Brexit was pushed forward by May at a crunch cabinet meeting at her countryside residence, called Chequers, on Friday.

In that meeting, May had appeared to win over her fractious cabinet and secure approval for her plan, which was to be published as soon as this week in a lengthy White Paper that would stake out Britain’s vision for future relations with Europe.

While May’s plan for exiting the European Union has not be fully revealed to all members of her party — let alone to parliament, the business community or the public — the brief outline that was released shows she supports a middle way of compromise with Brussels, keeping Britain closely aligned with Europe on standards,  “a common rule book for industrial goods and agricultural products.” This, her critic charged, would shackle Britain and make it a rule taker versus a rule maker.

May was scheduled to address all Tory parliamentarians at a meeting on Monday night.

Now some Conservatives who are pushing for a hard Brexit threaten that the prime minister soon face a no-confidence vote.

The British political press said more resignations might follow.

Reaction came thick and fast on Monday -- for those who were awake.

Some Brexit backers cheered Davis on. 

“Fantastic news,” tweeted Andrea Jenkyns, a Conservative lawmaker. “Well done David Davis for having the principal and guts to resign. I take my hat off to you. We need to make sure this is now a game changer for #Brexit.” 

Opposition lawmakers, meanwhile, said that this was a big blow for the prime minister. 

Jeremy Corbyn, the leader of the opposition Labour Party, tweeted that the resignation “at such a crucial time” showed that May “has no authority left and is incapable of delivering Brexit.”

“With her government in chaos, if she clings on, it's clear she's more interested in hanging on for her own sake than serving the people of our country,” he said.