The race to pick Japan’s sixth leader in five years was in turmoil after Ozawa, who heads the biggest group in the ruling Democratic Party of Japan despite facing trial over a funding scandal, reportedly refused to back the most popular candidate just days before the Aug. 29 ruling party vote.

Prime Minister Naoto Kan, who came under fire for his response to the massive March tsunami and the radiation crisis it triggered, confirmed his intention to step down at a gathering of ruling Democratic Party of Japan lawmakers, clearing the way for the party to pick a new leader on Monday.

Kaieda, 62, has called for an improvement in nuclear safety, arguing that Kan’s call to scrap nuclear power in the future is premature and more debate is needed. He has warned against a hasty rise in Japan’s sales tax and indicated he wants the Bank of Japan to do more to fight deflation.