TOKYO — Prime Minister Junichiro Koizumi scored a political triumph Sunday as the long-ruling Liberal Democratic Party headed for a landslide win in an election touted as a referendum on his push to privatize Japan's cash-swollen postal system.
Early Monday, public broadcaster NHK projected the LDP won 296 seats in parliament's 480-seat lawmaking lower house, far more than the 241 needed for a majority and the 249 seats it held when Koizumi dissolved the chamber Aug. 8. The most the party ever held was 300 of the body's then 512 seats in 1986.
Combined with the allied New Komei Party, the LDP-led ruling coalition would have more than 320 seats — a two-thirds majority that would let it override votes by the upper house, the body that blocked postal restructuring last month.
Official results were delayed by a minor counting error in one prefecture but were expected to be announced later today, election authorities said. The hotly fought election saw voter turnout jump seven points to 67.5 percent from the 2003 ballot, according to a Kyodo News Agency estimate.
"I had hoped we would win a majority with our party alone, but we did even better than that," a beaming Koizumi said late Sunday. "I thank the nation for its support and understanding."
Optimism about the results sent Tokyo's benchmark Nikkei stock index surging 1.8 percent to 12,915.53 points.
The win would keep a staunch ally of President Bush in power. Koizumi is expected to stand by his dispatch of troops to support the U.S.-led coalition in Iraq over opposition objections, and he strongly supports the continued presence of 50,000 U.S. military personnel in Japan.
Japan also is one of the United States' negotiating partners in the effort to disarm North Korea of its nuclear weapons.
In Washington, State Department spokeswoman Darla Jordan said the Bush administration looked forward to continuing to work closely with Koizumi's government and "to move ahead in our close cooperation on a broad range of global, regional and bilateral issues."
Victory was sweet for the popular leader, who called the election after defections within his party scuttled a legislative package he had championed for breaking up and privatizing Japan Post. He kept the campaign focused on his plan, overshadowing the opposition and rejuvenating the image of the LDP from staid ruling party to agent of dynamic change.
But the win also will test Koizumi's ability to make good on promise to transform the once-moribund, pork-barrel politics of the LDP into a streamlined force for dynamic reform and small government.
"If his policies and the party's stature betray the people's expectations, there will someday be a backlash," the Asahi newspaper said in a front-page analysis. "As soon as possible, he has to say what he will do after postal reform, and show concrete programs."
Along with delivering mail, Japan Post has savings and insurance programs with $3 trillion in deposits, making it the world's biggest financial institution. Koizumi contends putting those operations in private hands will bring more efficient lending of the cash and produce a bigger boost for the economy, which is the world's second-largest but has stagnated for years.
That seemed to resonate with a public worried that bloated government bureaucracies are sapping economic growth as the aging of the population raises questions about how Japan will pay for future retirees. Postal savings have long been used by the LDP as a slush fund for public works projects blamed for waste and corruption.
Though postal reform was likely to stay firmly at the top of Koizumi's agenda, a landslide would strengthen his hand in pushing other changes, including overhauling the national pension system and trying to rid the LDP of pork-barrel politics and refocus it on policy.
"We needed to hear the people's voice on reform," Koizumi said.
Though risky, his decision to call the elections was shrewd.
With voter attention riveted on his battle against the LDP defectors — he virtually booted all 37 out of the party, then sent out celebrity candidates to oppose them — the main opposition party found itself on the sidelines and was projected to suffer huge losses.
NHK predicted the centrist Democratic Party would likely end up with 113 seats, a disheartening plunge from its previous 175 seats.
Japanese media reported that LDP members had begun calling for Koizumi to stay on after his term as party president ends next September. Koizumi has said he intends to step down, however, and he repeated that vow Sunday.
The elections were sure to have deep repercussions on Japan's political landscape and speed the pace of government reforms.
"We did not expect this," said Katsuya Okada, who resigned early Monday as leader of the Democrats. "I don't think our policies were wrong, but we must reconsider our tactics."
The opposition's meltdown was all the more stunning because it came despite a high voter turnout, which usually plays in its favor.
"They had their shot and they blew it," said Gerald Curtis, a Japanese politics expert at Columbia University. "The LDP was and still is ready to be overthrown — the problem is it's been overthrown by its own president rather than the opposition."
One area that probably will not change is Japan's strained relationship with some of its neighbors, which have been angered by Koizumi's visits to a Tokyo war shrine that critics say glorifies Japan's militaristic past.