TOKYO (Kyodo) — Official campaigning for the race to choose the leader of Japan’s largest opposition party began Saturday as it gears up for a likely general election later in the year.

Yoshihiko Noda, 67, who served as Japan’s prime minister from 2011 to 2012 under the now-defunct Democratic Party of Japan, is one of four candidates in the Sept. 23 election for leader of the Constitutional Democratic Party of Japan.