Prime Minister Ishiba Shigeru announced his intention to step down on Sunday, 7 September, preempting what was likely to be an overwhelming defeat in a vote on whether to hold an early election.
The Liberal Democratic Party (LDP) will move quickly to set the rules and schedule for a new leadership election.
The LDP faces a difficult choice, as it seeks a leader who can unify the party, restore public trust, and work with opposition parties to restore the government’s control of the Diet.
Koizumi Shinjirō likely enters as the favorite, but could still face strong challenges from conservative Takaichi Sanae and others.