After he sensationally quit David Davis warned the United Kingdom is giving "too much away, too easily" in the exit talks, but backed May to remain prime minister after his dramatic resignation rocked her premiership.
But leading pro-Brexit lawmaker Jacob Rees-Mogg said he did not think she would face a leadership challenge. But a last-minute bit of steel is, in these febrile times, at least something.
"It is as though we are sending our vanguard into battle with the white flags fluttering above them", Johnson wrote in a letter that underscored his credentials as a champion of full-speed Brexit. He attacks May's plans in terms that, one imagines, were sharpened after No10 purposefully made a statement about his resignation before he had published his own.
Like Mr Gove - who infamously made a rival bid for the leadership after the referendum - Mr Johnson has always been suspected of aiming to lead the party and be prime minister.
Mrs May has now appointed Dominic Raab and Jeremy Hunt to replace Mr Davis and Mr Johnson.
May, having finally signalled her vision for Brexit, spent two hours in parliament defiantly defending the plans and called for Brussels to engage fully or risk the damaging prospect of Britain leaving the bloc with no deal in place.
Modric reveals Croatia biggest concern ahead of England clash
To that point, we had been allowing Spain to play their game, passing the ball like we all... But he is certainly well aware of the threat that Croatia pose in the centre of the field.
May has faced a backlash over the plan from Brexit hardliners in her Conservative Party who say it gives too many concessions to the European Union, but she has support from moderates and there has been no challenge to her leadership.
Pro-Europeans want to retain close economic ties with the bloc and its market of 500 million people, while some, but not all, Brexit supporters want a clean break to make it possible to strike new trade deals around the world. It would also necessitate the imposition of a border in Northern Ireland-a red-line issue for the European Union, and something May has committed to avoiding. They also argued that the proposals breach several of the "red lines" the government set out, including a commitment to leave the EU's tariff-free customs union. Specifically, she wanted to address the resignations of Johnson and Davis.
On Monday, May defended Friday's deal, which would allow for some ties between Britain and the EU.
Tory MPs can trigger a vote of no confidence if 48 of them submit letters to the 1922 backbencher committee, chaired by Sir Graham Brady. The timetable looks increasingly optimistic.
The prime minister was given backing by senior Tory figures from the Brexit and Remain sides as Downing Street tried to contain the rebellion by up to 80 members of the European Research Group of hard Brexiteers who attended last night's meeting.
Hunt, the MP for South West Surrey, has served as Health Secretary since 2012.