Tensions are once again running high between the Constitutional Democratic Party of Japan and the Japanese Communist Party. After the electoral damage suffered by the CDP in the Lower House election last October, when the party fielded unified candidates with the JCP, many question the logic behind trying the strategy again in this summer's Upper House election.

And with less than six months to go until the election, both opposition parties want to prevent the pro-constitutional revision ruling coalition and like-minded opposition parties from winning the necessary seats in the Upper House by splitting the anti-revision vote. But there appears to be no prospect for a compromise.

According to CDP leader Kenta Izumi, the idea doesn't seem worth revisiting. “It did not bear fruit," he said during a Fuji TV program on Jan. 31. "At this point, we’ve made it clear that we need to go back to scratch on what to do with the (electoral) cooperation.”