Japan's ruling coalition has soundly beaten the opposition in Sunday's election for the upper house of parliament. It appears that the extraordinary popularity of Prime Minister Junichiro Koizumi is behind the electoral victory.

Japanese voters gave Prime Minister Junichiro Koizumi and his economic reform platform a strong show of support in Sunday's upper house election.

While his name was not on the ballot, the vote is widely viewed as a barometer of public opinion on his plan to use tough measures to restore the country's economic health.

With all the votes counted, the unofficial tally shows Mr. Koizumi's Liberal Democratic Party and its two coalition partners, the New Komeito party and the New Conservative Party, won a combined 78 seats, well ahead of the 63 seats needed to maintain a majority.

The main opposition, the Democratic Party of Japan, won 26 seats, just below its target of 27.

In a television interview, the prime minister vowed to implement his dramatic reform plans, saying that leaving problems unsolved would ultimately mean greater pain.

He said the election results are better than he expected, adding that it is now his responsibility to put reforms in place with the cooperation of both the ruling coalition and opposition parties.

Yukio Hatoyama, the leader of the Democratic Party, acknowledges that even though some voters were disillusioned with the long-dominant Liberal Democratic Party, they were clearly willing to support its charismatic leader, Mr. Koizumi.

Mr. Hatoyama said the Democratic party, along with the citizens of Japan, will keep a close eye on Mr. Koizumi's stated aims to see whether they are achieved. He adds that the government must act quickly to clean up bad loans in the banking sector and to adopt structural reforms.

Despite his party's strong showing in the election, Mr. Koizumi is likely to face opposition from some formidable old-guard forces within his own LDP, who believe his reform plans are too radical.

Sunday's election is the first national poll since the Koizumi administration took office in April, following the resignation of the deeply unpopular Prime Minister Yoshiro Mori.

Official voter turnout was just over 56 percent, down slightly from the last upper house election in 1998.