Taro Kono is seen as a political maverick with liberal views on social policy. He is popular with the public, but his own party's power brokers may hesitate to make him the leader next week.

Prime Minister Yoshihide Suga's exit raises the specter of a return to a "revolving door" succession of Japanese leaders.

The former chief Cabinet secretary and government spokesman was sworn in as the country's first new prime minister in almost eight years after Shinzo Abe stepped down citing health concerns.