The pressure is on for a caretaker PM to replace Boris Johnson – but it won’t be easy

Even before Boris Johnson confirmed his intention to resign, the question has moved on to what will happen next. Will he continue as prime minister while the Conservative Party elects a successor, or will the party insist that Dominic Raab, the deputy prime minister, take over as a caretaker for the next few months?

The prime minister intends to stay on until the Tory party conference in October, while Sir Graham Brady, the chair of the 1922 Committee, says the new executive to be elected by Tory MPs on Monday will set the timetable for the leadership election. Normally, the outgoing prime minister remains in office until the end of that election, but Johnson has caused such chaos and destruction at the top of government in the past few days that the pressure for him to step aside immediately is going to be powerful.

Many Tory MPs feel that every day that Johnson is allowed to remain in office will do further damage to the party’s reputation, and make the next election harder to win. George Freeman, the science minister, who has written a letter of no-confidence but who hasn’t resigned, has argued for a caretaker prime minister.

The one thing that is likely to frustrate that plan is helpful advice from the Tory party’s enemies, headed by Nicola Sturgeon, the leader of the Scottish National Party, who has also said that a temporary prime minister should take over while the Tory leadership election is held. The only thing that is more likely to unite Tory MPs against the idea would be when Keir Starmer calls for it later today.

These are constitutionally tricky waters. There is no such post as caretaker prime minister: whoever is prime minister holds the full title and all its powers. The test ultimately is: who can command a majority in the House of Commons? Normally, that is the leader of the largest party, but now that leadership elections include party members outside parliament, these elections take longer than in the days when party leaders were chosen by MPs alone.

That means that, constitutionally, the Conservative Party has to decide that someone other than Johnson is its temporary leader and that the Queen should invite them to form a government. All eyes, therefore, on the new executive of the 1922 Committee which will be elected on Monday: its first business will be to decide the rules for the leadership election to replace Johnson. That could include special provision for a temporary leader, presumably Raab, but Johnson has already shown that he will try to fight until the last moment

The most striking phrase from Johnson’s spokesperson last night was: “He’s called their bluff.” This morning he decided to stop calling the bluff of his critics, and to accept the reality of his position, which is that he has lost the support of Tory MPs. But if he wants to stay on as prime minister, will the 1922 Committee or what is left of the cabinet stop him?

What is extraordinary is that, if Johnson had accepted the inevitable the moment that Rishi Sunak, the chancellor, resigned, no one would have disputed his right to remain in office until his successor were elected. Now there will be yet another titanic struggle to get him out of No 10 as quickly as possible.

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Expect some speculation about whether or not the final stage of the Tory leadership election, among party members, can be speeded up, but the mechanics of it cannot be compressed into less than several weeks.

Now that Johnson has yielded to the reality of his position among Tory MPs on the fundamental question – will he stay or will he go? – there will now be a struggle over the secondary question: will he go now?

There may be a rerun of the crisis of the past few days, as cabinet ministers, one by one, make it clear that Raab must take over for the next two months. If the cabinet as a whole recommends Raab to the Queen, she could be advised to call for him. I am not sure that Johnson can stop them, as it has become clear that he can’t replace cabinet ministers that he sacks.

What a fitting irony for the end of Johnson’s premiership that would be: that by trying to defy the constitutional convention to the end, he will have brought his time in No 10 to an end several weeks earlier than it need have done. And the ultimate insult would be that he would then serve as prime minister for a shorter period than Theresa May – Johnson needs to stay in office for another four weeks to overtake her tenure.