Prime Minister Theresa May has been dealt a fresh blow after her cabinet member Andrea Leadsom quit her post.
Mrs Leadsom, the Leader of the House of Commons, made the shock announcement tonight.
In a letter to Mrs May posted on Twitter "I no longer believe that our approach will deliver on the referendum result".
The Secretary of State for Environment, Food and Rural Affair's announcement came as the PM faces fresh calls to quit.
May has faced mounting pressure over her handling of Brexit.
And this week she had faced fury from Tory MPs after giving the House of Commons a chance to vote on a second Brexit referendum.
In her resignation letter, Leadsom told the Prime Minister there had been a "complete breakdown of collective responsibility" over Brexit" and urged her to "make the right decisions in the interests of the country, this Government and our party".
She said she "fundamentally opposes" portion's of May's new Brexit plan.
Labour Party chairman Ian Lavery, commenting on Leadsom's resignation from the Cabinet, said: "The Prime Minister's authority is shot and her time is up.
"While the Tories are ripping themselves apart, our country is in crisis. The Government has made a catastrophic mess of the Brexit negotiations, our steel industry is under threat and universal credit is pushing people into poverty.
"For the sake of the country, Theresa May needs to go, and we need an immediate general election."
Labour's deputy leader Tom Watson criticised Mrs Leadsom's decision to step down on the eve of the European elections, calling it a "slap in the face" for her Tory colleagues.
He tweeted: "I accept that she may want to go but to do it the night before an election looks odd.
"It's also a slap in the face to Tory party members who are working hard to get their candidates elected tomorrow."
Mrs Leadsom was one of a number of Brexit-supporting colleagues in the so-called Pizza Club who were absent for the start of Prime Minister's Questions on Wednesday.
A Downing Street spokesman said: "Andrea Leadsom has served with distinction and great ability as a member of the Government, and the Prime Minister is grateful for all of her work.
"We are disappointed that she has chosen to resign, and the Prime Minister remains focused on delivering the Brexit people voted for."
