Democratic Party heavyweight Yoshihiko Noda announced Tuesday he will step down from the main opposition party's No. 2 post to take responsibility for its crushing defeat in Tokyo's election earlier this month.

Noda's resignation as the party's secretary-general represents the centerpiece of a leadership shake-up engineered by its leader, Renho, as she seeks to revive the chronically struggling party that has fallen short of serving as a viable alternative to Prime Minister Shinzo Abe's ruling Liberal Democratic Party.

"I tendered my resignation to the party president as I think I should take heavy responsibility as secretary-general" for failing to steer the party properly, Noda told reporters at the DP's headquarters.