Naoto Kan, secretary general of the Democratic Party of Japan, said his party will postpone plans to push for a coalition government with two other opposition parties -- the Liberal Party and the Social Democratic Party.

"I don't think the talks on cooperation (in next summer's Upper House) election will develop into a coalition government plan in a single leap," Kan told a news conference Wednesday.

The three parties had earlier agreed to cooperate in some constituencies during the Upper House election, in an effort to prevent the ruling coalition from securing a majority in the chamber.