TOKYO - His popularity dented, Japanese Prime Minister Naoto Kan toned down his tax hike talk on the eve of parliamentary elections Sunday that are widely considered a referendum on the Democrats' 10 months in power.

Candidates traveled in campaign vans, speakers blaring and aides waving out of windows, stopping here and there to give speeches throughout the country Saturday.

The balloting, in which half the seats in the 242-member upper house are up for grabs, won't directly affect the ruling Democratic Party of Japan's grip on power because it has a hefty majority in the more powerful lower house that chooses the prime minister.

But recent polls show Kan's party will likely lose seats in the upper house, which could complicate its ability to pass legislation and force it to find new coalition partners.

Promising to cut wasteful spending and bring more transparency to politics, the Democrats swept to power in lower house elections last August that ended 55 years of nearly unbroken rule by the conservative Liberal Democratic Party.

So far, they have delivered mixed results. They have put the brakes on many large public works projects considered wasteful, but their first prime minister, Yukio Hatoyama, disappointed voters by breaking a campaign pledge to move a U.S. Marine base off the island of Okinawa and by getting mixed up in a funding scandal.

Kan, a plainspoken former finance minister with a grass-roots activist background, enjoyed an initial surge in approval ratings when he came to office just a month ago after Hatoyama's resignation.

Kan has argued that Japan needs to take aggressive steps to tackle its ballooning public debt as its population ages and declines. If it doesn't, he has warned that the world's No. 2 economy could face a Greece-like fiscal crisis - a comparison that experts say is a stretch because most government bonds are held by domestic investors.

But his suggestions that Japan should consider raising its sales tax from 5 percent to as high as 10 percent in coming years has weakened public support for his Cabinet and his party.

Over the last several days, Kan has changed his tack, promising that the Democrats won't raise the sales tax until after the next lower house elections, scheduled for three years from now, saying he wants to seek a public mandate for any decision. He has also spent more time talking about welfare and ways to promote economic growth.