Former Foreign Minister Seiji Maehara has promised to review the Democratic Party's cooperation with other opposition forces, including the Japanese Communist Party.
At a Monday news conference, Maehara said he will carry out the review if he is elected president of the DP, the main opposition party, in a Sept. 1 poll.
"Cooperating or forming a coalition with a party with totally different policies and philosophy is nothing but an unprincipled union," he said, stressing his negative view of teaming up with the JCP.
Maehara said the DP needs to become capable of replacing the ruling Liberal Democratic Party and its coalition ally, Komeito.
"We will aim for a change of government in the next election for the House of Representatives," he said.
Maehara did not rule out the possibility of cooperating with Tokyo Gov. Yuriko Koike, saying he will work with any parties that agree with the DP on policies and philosophy.
Maehara added that he still hopes to work with former DP Deputy President Goshi Hosono, who recently announced his intention to leave the party.