Transport minister Jo Johnson has quit the government, calling for the public to have a fresh say on Brexit.
The MP, who is Boris Johnson’s brother, said the withdrawal deal currently being negotiated with the European Union “will be a terrible mistake”.
Arguing Britain was “on the brink of the greatest crisis” since World War Two, he said what was on offer wasn’t “anything like what was promised”.
Downing Street thanked him for his work but ruled out another referendum.
Jo Johnson voted to remain in the EU while his brother Boris, who quit as foreign secretary in July, was a leading Brexiteer.
His brother praised his decision, saying they were “united in dismay” at the PM’s handling of the negotiations.
Cabinet ministers have been invited this week to read the UK’s draft withdrawal deal with the EU. Theresa May has said the withdrawal deal is 95% done – but there is no agreement yet on how to guarantee no hard border in Northern Ireland.
In an article sent to journalists, the MP for Orpington said he would vote against the withdrawal agreement in the Commons.
“Hopes for the ‘easiest trade deal in history’ have proved to be delusions,” he wrote.
“Contrary to promises, there is in fact no deal at all on our future trading relationship with the EU which the government can present to the country,” he wrote.
“While we wait to negotiate trading terms, the rules of the game will be set solely by the EU. Britain will lose its seat at the table and its ability to amend or vote down rules it opposes.”