Mujtaba Rahman is the head of Eurasia Group’s Europe practice. He posts at @Mij_Europe . British Prime Minister Keir Starmer’s premiership is entering its final phase. The U.K. leader may be insisting he will lead his Labour Party into the next election, but events both inside and outside the camp suggest otherwise. The real question is no longer whether Starmer survives, but who succeeds him, how and when. As widely reported, the pivotal moment could arrive via the Makerfield by-election on