TOKYO: Japanese Prime Minister Taro Aso's ruling party appeared to be heading for defeat Sunday in a Tokyo election seen as a crucial test of his popularity ahead of a nationwide vote, media reports said.

A drubbing by the opposition, which is seeking to end the ruling bloc's half-century of almost unbroken rule, could raise pressure on Aso from within his own party to quit before general elections he must call by September.

The opposition Democratic Party of Japan (DPJ) looked set to win the most seats in Sunday's vote for the Tokyo metropolitan assembly, public broadcaster NHK and Kyodo News reported based on their own projections.

With Aso's Liberal Democratic Party (LDP) and its coalition partner New Komeito also facing the possibility of losing their overall majority, the ruling bloc acknowledged its poor performance.

"We have to sincerely face the severe judgement from Tokyo residents," said a senior LDP official, Nobuteru Ishihara.

DPJ leader Yukio Hatoyama said that the opposition camp, which controls the upper house, would submit a motion of no-confidence against Aso "as soon as possible".

"We will urge (Aso) to ask for the people's voice by dissolving the lower house and calling a general election," he said.

Opinion polls suggest the LDP, having lost the upper house in 2007, is likely to lose its large majority in the lower house to the DPJ in the upcoming general election, triggering a major shift in Japan's political landscape.

Public support for Aso, who has been in office less than a year, has slumped over a series of ministerial resignations and concern about his stewardship of the economy during Japan's worst recession since World War II.

"This Tokyo election is the beginning of the path to a power change," said Tomoko Amatsuji, a 70-year-old office worker who voted for an opposition candidate. "I'm not satisfied with the government. It's time to see a change."

An opinion poll conducted by the Yomiuri Shimbun last weekend showed that 16.9 percent of Tokyo residents surveyed said they would vote for LDP candidates against 29.4 percent supporting opposition candidates.

Aso has argued that defeat to the DPJ in the Tokyo vote would not affect his desire to lead the ruling party through the upcoming national election.

"There is no direct link between the Tokyo assembly election and national politics," he was quoted by the government spokesman as saying on Saturday.

A total of 221 candidates, including 58 fielded each by the LDP and the DPJ, were vying for the 127 seats of the assembly, seeking support of 16.6 million eligible voters across the sprawling capital.

Before the vote, the ruling bloc had 70 seats -- 48 to the LDP and the rest to New Komeito -- against 34 held by the DPJ in the assembly. The polls closed at 8:00 pm (1100 GMT), with results expected late Sunday or early Monday.