Takahiro Yokomichi, chairman of the Executive Council of the Democratic Party of Japan, formally announced his candidacy in the party's presidential race Tuesday, saying he will make the war-renouncing Constitution one of the main focuses of campaign debate.

"I've decided to run for the DPJ leadership race this September," Yokomichi said in a press conference in Tokyo, after attending a meeting of former socialist Diet members supporting him.

Yokomichi stressed that there is no need to revise Article 9 of the Constitution, which bans the threat or use of force as a means of settling international disputes.