The Lower House passed a bill Tuesday that would cut five of its 300 districts amid mounting pressure to rectify vote-value disparities that have plagued national elections.

Most recently, the December general election has been ruled unconstitutional by several high courts due to disparities between districts.

The bill, which was moved to the Upper House for further action, would cut seats from Fukui, Yamanashi, Tokushima, Kochi and Saga prefectures, and reorganize 42 districts in 17 prefectures to bring the disparity down to 1.998 from 2.524. This is only slightly below the threshold of 2.0 that the Supreme Court deems is the upper permissible limit of disparity.

The Lower House passage virtually assures that the bill will become law during the current Diet session. Even if the Upper House refuses to take it up, the Constitution gives the Lower House the authority to pass a bill with a two-thirds majority, which the LDP-led ruling bloc has.

Opposition forces, including the Democratic Party of Japan and Nippon Ishin no Kai (Japan Restoration Party), assailed the bill for falling far short of bringing fundamental reform.

Last week, a bill submitted by the DPJ to cut 30 single-seat districts and 50 proportional-representation seats never made it to the Diet floor.

Although both parties boycotted the Lower House committee on this issue last week, only Nippon Ishin lawmakers made good on a threat to sit out Tuesday’s vote.

“We voted against the bill to show our intention to achieve sweeping reform during the current Diet session,” said DPJ Secretary General Goshi Hosono.