UK Prime Minister Keir Starmer has announced his resignation, triggering a leadership contest within the Labour Party. The selection process for his replacement will begin in July. Starmer intends to remain in office until a new leader is elected. The Labour Party anticipates having a new leader in place by September. This unexpected move initiates a period of political maneuvering as potential candidates emerge. Details regarding the specifics of the leadership election process are expected to be released shortly. The announcement follows a period of [information not provided in text - implied political context].