As Boris Johnson said on the day he announced his resignation - at Westminster, “when the herd moves, it moves”.
He was referring to the dozens of ministers who quit his government, forcing him to stand down against his will.
But the same groupthink has also gripped the Tory leadership contest, with the accepted wisdom being that Liz Truss is heading for an inevitable victory over Rishi Sunak.
Further evidence of this phenomenon came this morning, with Brandon Lewis the latest senior Conservative to publicly back the foreign secretary.
He followed on Tom Tugendhat yesterday and defence secretary Ben Wallace the day before.
With chancellor Nadhim Zahawi also expected to declare for her in the coming days, it is clear that the upper echelons of the Tory party have already made up their minds - Truss is heading for Number 10.
Of course, this doesn’t mean that they have all decided that she is uniquely blessed with the talents needed to lead the UK in such turbulent times. Indeed, Tugendhat and Zahawi were previously so unconvinced by Truss’s abilities that they ran for the leadership themselves.
But they have looked at both her and Sunak, and - crucially - the opinion polls, and concluded that this race is only ending one way, so they’d better hop on board the Truss Train before she decides who to give jobs to in her new administration.
That is not to say that all is lost for Sunak, however.
His campaign team are today pointing to a poll of Conservative councillors which only gives Truss a two point advantage over their man.
“This contest is all to play for,” said a Sunak campaign spokesperson. “Rishi is getting out there every day, visiting association after association across the country to meet members and earn every vote. The race has only just begun.”
But it is very hard to disagree with the assessment of another senior Tory who told HuffPost UK it is “all over bar the shouting”.
Tory members will begin receiving their ballot papers tomorrow, and many of them will cast their votes straight away.
If Sunak is to stand any chance at all, he will need to change their minds - as well as the direction of the herd - very quickly.
