Japan's Democratic Party won two by-elections for parliament's upper house today. Media projections showed a nod of voter approval in the first national polls since the party took power last month.

Prime Minister Yukio Hatoyama's Democratic Party of Japan (DPJ) ousted the long-dominant conservative Liberal Democratic Party to usher in a Government that promised to focus spending on consumers rather than companies and steer a diplomatic course less subservient to security ally Washington.

Public broadcaster NHK, citing exit polls and its own projections, said DPJ candidates were assured victory in the by-elections in Kanagawa near Tokyo and Shizuoka, southern Japan.

Hirokazu Tsuchida was also certain to win in Shizuoka, NHK said, Hatoyama has been riding high in opinion polls, with support rates of around 70%. But, the government faces tough challenges including worries about inflating an already bulging public debt as it seeks to fund ambitious spending programmes and concerns about friction in the US-Japan alliance, long the pillar of Japan's diplomacy.

Defeat in one or both of the polls would have been a disturbing sign for the novice administration, but voters sounded willing to give the month-old coalition time to prove itself. "Things are gradually starting to change, so I want to see how it goes," 74 year-old Wataro Sato said after casting a vote for DPJ candidate Kaneko in Kanagawa.

Even with the two victories, the Democrats are short of a majority on their own in the upper house, which although the less powerful of parliament's two chambers, can delay legislation. That means Hatoyama needs to rely on two tiny but vocal coalition partners, complicating policy decisions at least until an upper house election set for mid-2010.

A defeat for the DPJ and its allies in next year's poll would create a parliamentary deadlock similar to one that had stalled policies after 2007, when the Democrats and their allies took control of the chamber while the LDP dominated the lower house. "I have great expectations for them (the DPJ) but if things don't work out, I'll have to vote for someone else," retiree Sato said. Official tallies for the elections were due later today or early tomorrow.