Labour politicians have begun jostling to become the next leader of the British opposition party in the wake of its crushing defeat in last week’s national election. Keir Starmer, the party’s spokesman on Brexit issues, and senior lawmaker Yvette Cooper were among those suggesting Wednesday they were considering a run to replace Jeremy Corbyn in the race that heats up next year. The central question for party members is whether it was Labour policy or party leadership — or both — that led to the worst defeat since 1935.