Prime Minister Shinzo Abe will announce his candidacy for the Liberal Democratic Party's presidential race next month, sources familiar with the matter said Saturday.

Seeking to become Japan's longest-serving leader, Abe was initially expected to announce his plan for the September election on July 22, when the Diet is scheduled to close for the summer.

But he decided to postpone the announcement until August to focus on the devastation caused by the torrential rain in western Japan, which has left more than 200 people dead.

Former LDP Secretary-General Shigeru Ishiba, current policy chief Fumio Kishida and Internal Affairs and Communications Minister Seiko Noda are also considered possible candidates.

Abe might make the announcement on Aug. 11, when he meets with members of the party's chapter in Yamaguchi Prefecture, his base.

The race could be tough, however, as the opposition parties continue to grill him over the Moritomo Gakuen and Kake Gakuen favoritism scandals, which damaged his approval ratings substantially before a recent rebound. Abe has denied the allegations of cronyism.

The LDP is considering starting the official campaigning period on Sept. 7 and holding the presidential race on Sept. 20.