September 21 - Yoshihiko Noda is reelected as president of the Democratic Party for a full term, now changed to three years, against challengers Kazuhiro Haraguchi, Hirotaka Akamatsu and Michihiko Kano [REF].
September 26 - Shinzo Abe succeeds Sadakazu Tanigaki as president of the Liberal Democratic Party (official campaigning started on September 14).