Campaign cooperation in the Upper House election next year may make sense for opposition parties if they hope to dent the dominant grip on power by Prime Minister Shinzo Abe's ruling coalition. The question is whether they can come up with a minimum set of common positions on which they can justify the move with their supporters — and demonstrate to voters what they aim to achieve by working together.

Talks are under way among leaders of the five parties that opposed the security laws the Abe administration jammed through the Diet during the last session — the Democratic Party of Japan, Ishin no To (Japan Innovation Party), Japanese Communist Party, Social Democratic Party and Seikatsu no To (People's Life Party) — on ways to cooperate next summer to boost their chances against the Liberal Democratic Party-Komeito alliance.

Since the DPJ's fall from power in the 2012 Lower House election, the splintered opposition camp has been dwarfed by Abe's ruling alliance both in Diet proceedings and electoral performance. They have been no match for the coalition candidates, particularly in most of the winner-take-all races in single-seat districts. The ruling bloc swept 232 seats from the 295 electoral districts at stake in the Lower House election last December. In the last Upper House election in 2013, the LDP won 29 of the 31 constituencies where one seat each was up for grabs. The overall results next year are again expected to hinge on the outcome in the 32 constituencies where one seat each will be up for election.