The ordinary session Diet ended Wednesday, with political parties effectively launching their campaigns for the upper house election next month in which voters will give their judgment on the administration of Prime Minister Shinzo Abe formed in late December.
The 150-day session ended with the passage in the upper house of a censure motion against Abe. The Diet failed to vote on some bills, including one to enable the government to initiate a series of reforms of the Japanese power sector.
"I must not lose this House of Councillors election and must definitely end the divided Diet," Abe told a press conference, referring to the opposition-controlled upper house.
The censure motion accused Abe and his Cabinet ministers of refusing to attend upper house Budget Committee sessions on Monday and Tuesday in protest at the handling of the chamber by its president, Kenji Hirata of the Democratic Party of Japan.
The ruling coalition led by Abe's Liberal Democratic Party filed a no-confidence motion against Hirata, but it was rejected by the upper house.
By skipping the committee sessions, Abe "made light of (the principle of) popular sovereignty," three small opposition parties said in filing the censure motion.
The ruling bloc had criticized Hirata for not holding deliberations in the upper house on a bill to reform Japan's electoral system, even after receiving the bill from the House of Representatives, which passed it in April.
Opposition parties saw the bill as only partially addressing problems in the system and urged Abe to draw up more comprehensive reform plans, including a sharp reduction in the number of Diet seats.
The revision legislation was finally enacted Monday after a vote in the more powerful lower house, where Abe's ruling camp holds a majority.
Abe is the fourth Japanese prime minister to have a censure motion passed against him in the upper house, following his predecessor Yoshihiko Noda of the DPJ-led government last August.
The motion is legally nonbinding, unlike a no-confidence motion against the government in the lower chamber, which forces the dissolution of the lower house for a general election or the resignation of the Cabinet en masse.
However, the latest motion stung Abe ahead of an upper house election, expected on July 21 with official campaigning starting July 4. The Cabinet is expected to decide on the schedule soon.
The smaller opposition parties' efforts to censure Abe gained momentum after the DPJ endorsed the move in an apparent U-turn.
The DPJ had earlier been reluctant to join them, citing the need to deliberate on pending bills in the upper house that needed to be voted on by the final day of the ordinary session.
The conflict in parliament forced parties to scrap a total of six bills, including one to achieve the first part of a sweeping overhaul of the country's power sector that would fully liberalize the retail electricity market in 2016.
Also abandoned were bills aimed at preventing abuse of welfare benefits and to protect domestic aquatic resources from uncontrolled acquisition or development by foreign "water majors."