Ending weeks of speculation, Prime Minister Shinzo Abe announced Friday that he is stepping down for health reasons a second time, leaving Tokyo scrambling to make the transition to a post-Abe era.

Attention has now shifted to who will replace Abe and when. The nation’s political nerve center had recently been abuzz about whether Abe would resign over his chronic ulcerative colitis, a bowel disease.

Abe said he will stay on as prime minister until his successor is chosen. His Liberal Democratic Party is expected to hold a party presidential election by the end of September, with Diet lawmakers and three representatives from each of the 47 local chapters voting, but not rank-and-file party members.