The race to choose Japan’s sixth leader in five years is in turmoil after the decision by Naoto Kan to stand down.
The prime minister had said he would quit once parliament passed three key pieces of legislation, which it’s now done.
MPs from the ruling Democratic Party of Japan will pick a new leader on Monday, but the most powerful figure in the party is reportedly refusing to back the most popular candidate.
Naoto Kan told a news conference he was stepping aside as party chief, and as soon as it chose a new leader he would resign as prime minister.
His successor faces huge problems. A strong yen threatens exports and the country has to fund an increasingly ageing society.
The earthquake and tsunami that sealed Kan’s fate have left the challenge of long-term reconstruction.
Japan’s commitment to rely less on nuclear power means a new energy policy is needed.
Former foreign minister Seiji Maehara is the voters’ preferred successor, but there are several contenders and the ruling party is divided.