More than 50 people on the government payroll resigned in protest at Johnson’s handling of the Christopher Pincher affair, with many citing broader concerns about standards in public life. A total of 26 ministers have stepped down, by far the largest mass ministerial resignation in modern British history.
Johnson’s fate was sealed on Thursday (7 July) when Sunak’s replacement, Nadhim Zahawi, publicly called for his resignation. Zahawi’s replacement as education secretary, Michelle Donelan, resigned after just 35 hours in the job.
The question now is whether Boris Johnson can remain Prime Minister until a successor is chosen, as Theresa May did before him. Johnson reportedly plans to stay in post until the Conservative Party conference in October, but it remains unclear whether he would be able to fill the ministerial posts that have been left vacant.
The Defence Secretary, Ben Wallace, has called for Johnson to leave sooner in order to keep the government running, a message echoed by the Business Secretary, Kwasi Kwarteng, and another former minister, George Freeman. Johnson's former adviser Dominic Cummings has called for Johnson to go immediately and for the Deputy Prime Minister, Dominic Raab, to succeed him as interim prime minister.
Parliament is due to break up for the summer recess on 22 July. If Johnson leaves office before that date, he will have served a shorter term than May.
The Attorney General, Suella Braverman, is currently the only Conservative MP to have publicly announced a leadership challenge, though more are expected to put themselves forward in the coming days.
Betting markets currently give Sunak and Penny Mordaunt, the former trade minister, the best chance at succeeding Johnson as Conservative leader. Sajid Javid and Wallace are also considered possible contenders.
[See also: Boris Johnson has not resigned as Prime Minister]