Health Secretary Sajid Javid and Chancellor of the Exchequer Rishi Sunak have resigned after days of mounting pressure on Downing Street over their handling of allegations of sexual harassment by a member of the government. Johnson has weathered many storms during his tenure as Prime Minister, but this may be one crisis too many. Here’s what you need to know.

HOW DID WE GET HERE?

The immediate cause of the crisis was the fallout from the resignation last Thursday of Deputy Chief Whip Chris Pincher amid allegations he had abused two guests at a private dinner the night before. What got Johnson into deeper trouble, however, were the contortions Downing Street press officers indulged in when trying to explain why Pincher was ever in government. At first, when new reports emerged about Pincher’s historic behavior in light of his resignation, Downing Street denied the Prime Minister knew anything about the allegations, which related to Pincher’s time as foreign secretary. When it became clear that would not be the case, Johnson’s team said they were aware of the historical allegations but that they had been “resolved”. When it was revealed that one of the previously unreported allegations against Pincher had been upheld, Johnson’s spokesman explained that “resolved” could mean it had been upheld. Then on Tuesday morning, Simon McDonald, a former senior civil servant at the Foreign Office, revealed that Johnson had been told in person of the outcome of an inquiry into Pincher’s conduct, prompting a wave of resignations throughout the day.

WHAT HAPPENS NEXT?

Boris Johnson still controls his own destiny … for now. Conservative Party rules dictate that if a leader wins a vote of confidence then they are immune from another challenge for 12 months. Johnson survived a confidence vote on June 6. However, so deep is the current crisis that it is possible that the 1922 Committee of Conservative MPs will rewrite the rules to get rid of the Prime Minister. The 1922 executive body is expected to meet Wednesday to set a date for elections to its committee. If a large enough number of anti-Johnson MPs are elected to the executive branch, then the chances of changing the rules increase dramatically. Until that point, the real question is how much public humiliation can the Prime Minister take? More ministers are almost certain to resign and opposition sources are discussing the prospect of defections.

WHAT HAPPENS IF JOHNSON RESIGNS?

In the UK, the resignation of a prime minister does not automatically trigger a general election. If Johnson were to leave, the Conservative Party would hold an internal election to choose a new leader, who would then become prime minister. Johnson would likely remain in the post until a successor is chosen, as his predecessors Theresa May and David Cameron did when they stepped down in May 2019 and June 2016 respectively. Barring another resignation or snap election, the new prime minister will lead the UK until the next scheduled election in 2024.