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.

“Our plan to rectify the constituency allocation is based on the legislator-sponsored legislation that was passed in the Diet last year. It’s puzzling why they are opposed to it,” LDP Secretary General Shigeru Ishiba said after the meeting.

Instead, the opposition camp demanded a drastic seat reduction in the Lower House.

“We could not agree on the plan as the LDP toned down its willingness to reduce the number of seats from a ‘promise’ to ‘best effort,’ ” said Yorihisa Matsuno, acting secretary general of Nippon Ishin no Kai (Japan Restoration Party).

Despite the breakdown in negotiations, the ruling camp, which holds more than two-thirds of the seats in the Lower House, could resort to steamrolling the legislation through the chamber if no compromise is struck before the LDP-sponsored package is submitted April 12.

Ishiba said both camps agreed to continue the discussions.

The LDP plan was initially compiled based on the agreement last year between Prime Minister Yoshihiko Noda of the then-ruling Democratic Party of Japan and LDP President Sadakazu Tanigaki that they would first correct the vote disparity before working on fundamental changes to the number of seats, following the Supreme Court’s decision in March 2011 that the 2009 general election was “in a state of unconstitutionality.”