Keir Starmer said he would step down as Britain’s prime minister after suffering a precipitous fall from favor, paving the way for Andy Burnham to bid to succeed him.

In a dramatic announcement Monday morning in Downing Street, Starmer said he would step down first as Labour leader, with nominations for a successor opening July 9 and any contest wrapped up by the end of Parliament’s summer break on Sept. 1. He said he would remain in office until the process is done, and “ensure an orderly handover of power” to the winner.

“The question my party is asking now is whether I am best placed to lead us into the next general election. I have heard the answer of my parliamentary party,” Starmer said, adding that he accepted their verdict of him with “good grace.”

Starmer’s exit opens the door to Britain’s fifth premier since 2022: a jarring milestone for a political system which once prized itself on its stability. Burnham is Starmer’s most likely successor, not least because last week he roundly defeated Reform UK to win his parliamentary seat in Makerfield, near Manchester. Under Starmer Nigel Farage’s populist outfit, which leads national polls of voter intention, had swept all council seats available in local elections on the same turf just six weeks earlier.