The Diet's deepening divide was revealed Monday as the ruling camp led by Prime Minister Shinzo Abe's Liberal Democratic Party bulldozed through an electoral reform bill in a manner not seen since 2008.
The bill, which will reduce the number of lower house seats to ease the disparity in the weight of votes, was approved in the powerful House of Representatives by a more than two-thirds majority after the opposition-controlled House of Councillors was deemed under a constitutional provision to have rejected the bill.
Under Article 59 of the Constitution, a bill can be passed by the lower house with a two-thirds majority if the upper house fails to vote on it within 60 days of receiving the bill from the lower house.
The lower house approved the electoral reform bill in its first vote on April 23, but the upper chamber refused to deliberate the bill and the 60-day deadline passed last Friday.
Taking a second vote in the lower house based on the constitutional provision has not been resorted to since 2008.
Abe has been increasingly confrontational with opposition parties, apparently encouraged by the recent high approval ratings for his Cabinet, ahead of an upper house election next month that could lead to an end to the divided Diet.
The election reform comes as Abe has been trying to respond swiftly to a series of high court rulings this year that have judged the current disparity in vote value between the most and least populated constituencies as unconstitutional, with two of the rulings having concluded that the result of last December's general election, in which the LDP returned to power, is invalid.
The bill for revision to the Public Office Election Law will reduce the number of single-seat constituencies for the lower house to 295 from 300 while rezoning districts, reducing the biggest gap in vote values to below two times, in line with recommendations by an advisory panel in parliament.
Opposition parties have criticized the bill, saying it is insufficient and calling for a bigger cut in the number as quickly as possible. Abe, meanwhile, has said the five-seat reduction is the first in a series of reform measures, promising more work will follow.
Reforming the electoral system to downsize parliament is a highly focused issue in Japan as lawmakers show their willingness to "accept pain" at a time when they will place more burden on taxpayers. The Diet approved legislation last August to raise the nation's sales tax rate from next April.
The parliamentary row over the electoral reform bill came ahead of the upper house election, expected on July 21, in which Abe's ruling coalition will strive to secure a majority to break the impasse caused by the divided Diet.
Should the ruling bloc regain control of the upper house, it would give Abe more leeway over policy and help accelerate government efforts to revive the moribund economy.
Prospects for such a scenario seem brighter for Abe after the ruling alliance won an overall majority in the Tokyo metropolitan assembly election on Sunday, with all candidates fielded by the LDP and the New Komeito party obtaining seats.