The opposition-controlled upper house on Wednesday night passed a censure motion against Prime Minister Yoshihiko Noda by 129 to 91 votes, piling more pressure on him to make good on the promise to call an early election.
The reprimand is non-binding, but effectively means that the opposition will stop cooperating with the government on most bills, including key ones on deficit financing and voting reform that need opposition votes to pass.
Early this month, Noda promised to call an early election as the price for opposition support for his plan to raise the sales tax to offset rising social security costs.
But to the growing frustration of his rivals, he has since been coy on the timing of the vote and last week brushed off as speculation reports that he had suggested a November date in his talks with opposition leaders.
No one expects the Diet to serve its full term that ends in August 2013, but many of Noda's Democrats want to push back the vote as opinion polls show they would lose badly.
By threatening to stall the bill that the government needs to cover the bulk of its fiscal deficit and 40 percent of all spending, the opposition hopes to finally win his unequivocal commitment.
Five months into this fiscal year, the government has made do by dipping into reserves and making other adjustments. But Finance Minister Jun Azumi has warned that the government could run out of cash by early October if the bill fails to pass.
In its censure motion that it later merged with one submitted by smaller parties, the main opposition Liberal Democratic Party and its main ally New Komeito Party accused Noda and his government of incompetence in handling state matters.
In particular, it called recent territorial spats with South Korea, China and Russia a "national crisis" caused by incoherent foreign policy.
The Democrats on Tuesday passed the deficit-financing bill in the lower house they control and an election reform bill to correct a bias that favours rural voting districts. However, the opposition boycotted both votes, signalling the bills had little chance of clearing the upper house.
Several ruling party and opposition lawmakers have suggested that Noda would probably wait out the stalemate until the current Diet session ends on Sept 8 and call a snap vote during an extra session in October to secure the bills' passage.
An election is likely to end the DPJ's three-year rule, though opinion surveys suggest the poll may fail to produce clear winners, given the high percentage of undecided voters and general disillusionment with mainstream parties.
The DPJ, a mix of conservatives, center-left lawmakers and ex-socialists, swept to power in August 2009, pledging to change how Japan was governed after more than 50 years of almost non-stop rule by the conservative LDP.
Three years and three prime ministers later, critics say the Democrats have largely failed to deliver on promises to reduce bureaucrats' control over policymaking and pay more heed to families.
The party has also suffered defections over the tax increase and is divided as Noda tries to devise a national energy policy amid a growing anti-nuclear clamour after last year's Fukushima atomic disaster.© (c) Copyright Thomson Reuters 2012.