Democratic Party of Japan kingpin Ichiro Ozawa plans to back industry minister Banri Kaieda out of the five candidates who have announced they will run in the party's presidential election next week.

Kaieda on Friday night became the fifth DPJ heavyweight to declare his candidacy after Prime Minister Naoto Kan made it official the same day he is stepping down.

"I want to fight (the other candidates) with Mr. Ozawa's support," Kaieda said at a Friday news conference in Tokyo. Speaking at the same event, Ozawa called on DPJ lawmakers to unite behind Kaieda.