Amid a spate of high court verdicts that the vote-value disparity in the December Lower House election was either unconstitutional or invalid, the opposition camp on Wednesday rejected the ruling coalition's plan to rectify the problem.

The rejection could lead to more Diet gridlock. The ruling camp-held Lower House could possibly override a vote on the matter in the opposition-controlled Upper House.

At a meeting of the ruling and opposition secretaries general, all of the opposition parties except Shinto Kaikaku (New Renaissance Party) opposed the Liberal Democratic Party-New Komeito plan to cut five single-seat Lower House districts from the current 300 to bring down the vote disparity below 2-1.