The main opposition Constitutional Democratic Party of Japan held a briefing session on its Sept. 23 leadership election on Monday, with seven possible candidates' camps in attendance.

The seven include former CDP leader Yukio Edano, 60, who has already announced his candidacy, as well as current leader Kenta Izumi, 50, and former Prime Minister Yoshihiko Noda, 67.

The other four are CDP Executive Deputy President Chinami Nishimura, 57, former Executive Deputy President Kenji Eda, 68, former land minister Sumio Mabuchi, 64, and freshman lawmaker Harumi Yoshida, 52.

Speaking to reporters Monday in the city of Narashino, Chiba Prefecture, Noda suggested that his party may need a toned-down figure like himself compared to the many seemingly flamboyant candidates running in the ruling Liberal Democratic Party's leadership race, also set to be held next month.

"The next (CDP) leader may be required to have a sense of stability rather than a sense of renewal," the former prime minister said in a post on his website.

Also on Monday, Izumi received 106 signatures from regional assembly members calling on him to seek reelection as CDP leader. Reiterating his eagerness to stay on, Izumi told reporters, " I want to go ahead with preparations with enthusiasm while consulting with my colleagues."

Yoshida separately told reporters, "I want to spark debates from the perspective of a woman in touch with daily life." She was elected to the House of Representatives for the first time in the previous general election, defeating former LDP Secretary-General Nobuteru Ishihara in the Tokyo No. 8 constituency.