TOKYO (AP) ― Japanese Prime Minister Naoto Kan announced Friday he was resigning after almost 15 months in office, amid plunging approval ratings over his government’s handling of the tsunami disaster and nuclear crisis.

Kan’s resignation perpetuates the high turnover in Japanese political leadership at a time when the country faces huge problems, including an aging population and sluggish economy ― and now reconstruction from the worst disaster to hit the country since World War II.

In a nationally televised speech, Kan said he was stepping down as chief of the ruling Democratic Party of Japan, effectively ending his tenure as leader of the country. The decision was widely expected because in June, Kan had promised to quit once lawmakers passed three key pieces of legislation, the final two of which cleared the parliament earlier Friday.

The Democrats will vote Monday for a new leader, who will almost certainly become Japan’s next prime minister ― the sixth since 2006. Kan managed to survive only a few months longer than the four previous prime ministers, who each lasted a year or less.

Former Foreign Minister Seiji Maehara, a 49-year-old expert in defense and a China hawk, is viewed as the front-runner to replace Kan. Finance Minister Yoshihiko Noda and Trade Minister Banri Kaieda are also viewed as contenders.

Looking back on his year and three months in office, Kan said he did all he could given difficulties he faced, including the disasters and a major election defeat in upper house elections last summer that left the parliament in gridlock.