Tensions in the Conservative party over Brexit are deepening ahead of a crunch Cabinet meeting on Friday aimed at resolving Britain's future in the European Union once and for all.
On Monday evening, Boris Johnson leapt to the defence of arch-Brexiteer Jacob Rees-Mogg after he wrote an article warning the prime minister that she risks a Tory revolt if she fails to deliver the Brexit she promised.
And it emerged that Leave-backing Tory backbenchers have written an open letter to Theresa May setting out their red lines for Brexit – including no extension of the transition period beyond December 2020.
The foreign secretary intervened after a day in which his ministerial colleagues – including his own Foreign Office deputy Alan Duncan – tweeted their disappointment at Rees-Mogg's apparent threat.
It's vital that all MPs are able to air their views on Brexit. Whatever your position, I hope we can all agree that @Jacob_Rees_Mogg is a principled and dedicated MP who wants the best for our country.
He was later supported by Brexit minister Steve Baker.
Quite right https://t.co/WzaAQjV7Te
It came after Rees-Mogg, who leads a group of Eurosceptic Tory MPs, wrote in the Daily Telegraph that he and his colleagues will vote against Theresa May's deal if she fails to "deliver what she has said she would".
He compared the PM's position to that of former Tory party leader Sir Robert Peel, who was forced to resign after his party revolted over the repeal of the Corn Laws.
Rees-Mogg's words made the front page of the newspaper – sparking fury among loyal frontbenchers who called on the party to stay united ahead of crucial Brexit negotiations.
Duncan, minister for Europe and the Americas, tweeted that "the ideological right are a minority despite their noise".
😳Enough. Just tired of this endless threat and counter threat. Why don’t we want the best for the U.K. than for our own ideological cliques? And there are others in this negotiation as far as I’m aware? https://t.co/bPL517qt3p
And Alistair Burt, minister for the Middle East, said he was tired of the "endless threat and counter threat".
In the House of Commons on Monday, May explicitly refused to rule out extending the Brexit transition period beyond December 2020.
She did, however, confirm that keeping the UK in the EEA (European Economic Area) – the “Norway” option – would, in her view, "not deliver on the vote of the referendum and the vote of the British people."
In response to Johnson's tweet, Rees-Mogg replied: "Thank you."
Thank you. https://t.co/fCpeK9kn3B
A letter coordinated by Tory MP Andrea Jenkyns called on the PM to "get tough in your negotiations with the European Union", although it was not immediately clear which other backbenchers had signed it.
It said MPs would not accept any extension of the transition period or the jurisdiction of the European Court of Justice over the UK in any form beyond this time. It also states that Britain must not remain part of the customs union.
Cabinet ministers are meeting at Chequers on Friday for a day-long discussion on the future trading relationship with the EU, amid warnings that they will be unable to secure a bespoke agreement.