By any normal metric it is fair to say Boris Johnson is doomed, given the scale of ministerial resignations and the number of backbench MPs publicly withdrawing their support. While Johnson has often defied normal political rules, it does seem a matter of when he is ousted from No 10 rather than if. But how? Here are some scenarios. A change of party rules and new confidence vote A month ago, battered by a previous wave of controversies over Downing Street parties, Tory MPs called a confidence vote in the prime minister, which he won, albeit with 41% of parliamentary Tories wanting him out. Under party rules, winning such a vote means a leader is safe from a similar challenge for 12 months. However, these rules can be changed, and the key to that is the 1922 Committee, the official caucus for backbench Conservatives. Next week MPs will elect a new executive for the committee, with several candidates standing on an explicit platform of rule change so that Johnson can be removed quickly. Perhaps the most likely scenario for Johnson being kicked out is a change of rules and a new confidence vote, possibly even before the summer recess. Losing a confidence vote closes the argument for a Tory leader – they are out. Likelihood rating: 3/5 A managed exit, AKA a visit from the men in grey suits A variant of the above is what happened to Theresa May, whom Johnson played a significant role in removing as prime minister before he replaced her. This would see Johnson, like May, offered a deal by leading backbenchers: announce an imminent date for your departure, or we will change the party rules and get rid of you anyway. As well as offering some dignity to the ousted prime minister, it would also allow a leadership contest to take place with continuity inside No 10. For many leaders as embattled as Johnson, this would be the obvious way out. However, it relies on him being logical and wanting the best for the Conservative party and government, neither of which are a given. Likelihood rating: 2/5 Johnson walks out This would, in some ways, be the most straightforward solution, even if it would require an interim PM to keep the seat warm while a new Conservative leader is selected. Dominic Raab is deputy PM and would be the obvious choice, though matters could be complicated if Raab were to run to succeed Johnson. Such an outcome could be tempting for Johnson: just walk out, perhaps even resign as an MP, and be free of not just political worries but also any constraints on making huge sums of money on the lecture circuit. He could even write his much-delayed book on Shakespeare. But for a man often dismissed as a dilettante, Johnson can be surprisingly stubborn. He has thus far always dismissed this option, talking instead about ruling into the 2030s. But anything could happen. Likelihood rating: 2/5 A slow bleed-out This scenario is, in essence, a variation on any of the above three – there is no defining end point for Johnson, but days or weeks of ministers resigning and MPs calling for him to go while the prime minister metaphorically boards himself up inside No 10. This would be deeply damaging for Johnson, not to mention the government and the country. But he has, on a number of occasions during his brief time in power, done things that pundits declared could never happen. It would, of course, have to end, most likely in a confidence vote. But with such a disparate group of rebels, and the Commons recess coming, such a last stand could go on for months. Likelihood rating: 1/5