Boris Johnson is demanding a show of defiance from Theresa May after Brexit talks collapsed amid further clashes over the future of the Irish border.
At the start of a make-or-break week for the prime minister which could determine how long she survives, he said a crisis was looming and urgent action was needed.
The former foreign secretary re-opened hostilities against Mrs May after talks in Brussels between Brexit Secretary Dominic Raab and the EU’s Michel Barnier broke down after little more than an hour.
Writing in his Daily Telegraph column, Mr Johnson declared: “There comes a point when you have to stand up to bullies.
“After more than two years of being ruthlessly pushed around by the EU, it is time for the UK to resist.
“With painful politeness, we have agreed to the EU’s timetable for discussions. We have consented to hand over huge quantities of taxpayers’ money – £39bn of it.
“We have quite properly volunteered to protect the rights of EU nationals in the UK. So far we have nothing to show for our generosity and understanding.
“We are now entering the moment of crisis. Matters cannot go on as they are.”
Mr Johnson’s call to “stand up to bullies” echoes almost word for word a similar call for defiance against Brussels by fellow Brexiteer Jacob Rees-Mogg as he shared a platform with Nigel Farage at a Leave Means Leave rally in Torquay.
For Mrs May, who is facing battles against Brussels, Brexiteers and the Democratic Unionist Party, her already difficult week now looks fraught with danger:
:: On Monday, MPs want Mr Raab to come to the Commons to explain why his Brussels talks with Mr Barnier collapsed.
:: Talks will also take place between the DUP leader Arlene Foster and Irish leader Leo Varadkar, while Mrs May will meet Sinn Fein leader Mary Lou McDonald in Westminster.
:: On Tuesday, the prime minister chairs a Brexit cabinet, with ministers including Andrea Leadsom, Penny Mordaunt and Esther McVey threatening to resign.
:: And on Wednesday, after Prime Minister’s Questions, she heads for Brussels for a summit with EU leaders at which she had hoped for a breakthrough.
Mr Raab’s talks collapsed because the prime minister warned that the proposed deal was a non-starter that would be rejected by her cabinet, her backbenchers and the DUP.
As it has been for several months, the main dispute was over the Northern Ireland backstop – a guarantee of no hard border between Northern Ireland and the Irish Republic pending a UK-EU trade deal.
Calling for the backstop to be jettisoned, Mr Johnson writes in the Telegraph: “In presuming to change the constitutional arrangements of the United Kingdom, the EU is treating us with naked contempt.
“Like some chess player triumphantly forking our king and our queen, the EU Commission is offering the UK Government what appears to be a binary choice.
“It is a choice between the break-up of this country, or the subjugation of this country, between separation or submission.”
While the Brussels talks were going on, Foreign Secretary Jeremy Hunt attempted to maintain a sense of humour by posting an image of himself and other foreign ministers waving from the heart of a maze.
Mr Hunt, meeting eight of his counterparts at Chevening, his country residence in Kent, tweeted: “Challenged a few of my fellow foreign ministers to navigate the Chevening maze in the rain… by comparison to which Brexit discussions seem more straightforward.”
But he also had a serious message on the Brexit talks, telling Sky News: “It’s important we have a backstop for Ireland so we don’t see a return to the troubles.
“We can’t solve the issue around the backstop by carving up the UK however with a border down the Irish sea.”
Despite the breakdown in talks, the government says the prime minister is still committed to making progress at the EU summit later this week, even though no further negotiations are planned before then.
But amid the febrile atmosphere among Conservative MPs, the government chief whip Julian Smith posted another bizarre tweet by a senior Tory, showing a telephone off the hook.
It was clearly a message urging his frenzied backbenchers to calm down. Or perhaps a message for Mr Barnier.