Up until now, the Tory leadership rules have protected Boris Johnson. The requirement that 15 per cent of MPs must send in a letter sets a high bar for a no-confidence ballot, as demonstrated by how long it took the rebels to get the numbers against both Johnson and May. But from now on, the rules work against him.
The reason for this is that because the bar is so high for a no-confidence ballot it means that a substantial number of the leader’s own MPs will vote no confidence in them. Once that has happened it cannot be undone. Johnson will be wounded by the result tonight even if he wins. If he gets less than the 63 per cent of the vote that Theresa May got, he will be in a particularly bad way.
The worry for Johnson is that it is hard to see how he could bring the party back together even if he wins tonight. The only thing unifying the rebels is their opposition to his leadership, there is no policy solution that would placate them. (Indeed, if the rebels were more organised they might have had the strategic patience to wait until after the by-elections on 23 June at which point it would have been more likely for Johnson to lose). So, the rebels will keep coming, keep pressing for a rule change that will allow another vote within a year.
Johnson will likely win tonight’s vote. But that does not mean he will lead the Tories into the next election or even that he is safe for another year. He will now be engaged in a daily fight for survival.