Japan's Prime Minister Naoto Kan (R) bows to Fukushima Governor Yuhei Sato at the Fukushima prefectural office in Fukushima, in this photo taken by Mainichi Shimbun April 21, 2011. [Photo/Agencies]

TOKYO - Unpopular Japanese Prime Minister Naoto Kan is likely to face fresh pressure to quit after his ruling party's poor performance in local elections on Sunday, weakening his clout as he struggles to contain a nuclear crisis and find ways to finance rebuilding from a massive earthquake and tsunami.

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Kan is unlikely to step down easily, but the outcome of the polls will likely make it harder to get opposition cooperation in figuring out how to fund rebuilding from disasters that caused up to $300 billion in damage, a tough task given a public debt twice the $5 trillion economy.

Such cooperation is vital given a divided parliament.

"I don't think the results of the elections will lead to any quick resolution, but it is true that the opposition parties will feel emboldened to be obstructionist," said Sophia University professor Koichi Nakano.

Japan's Democratic Party of Japan (DPJ) lost six out of nine mayoral races in which it faced off directly against its main opposition, the Liberal Democratic Party (LDP), and lagged behind in a spate of city assembly elections across the country, Japanese media reported, although the LDP itself lost seats.

An LDP candidate also romped to victory in a lower house by-election in the former Democratic Party stronghold of Aichi, central Japan, after the DPJ failed even to field a contender.

"The election results show that (voters) have filed a huge complaint against the Kan cabinet over its handling of the disasters," LDP President Sadakazu Tanigaki told a late night news conference. "This shows that many voters are worried whether he is really capable."

Declining Clout, Continuing Deadlock

Kan brushed aside criticism of his handling of the disasters.

"We must accept the results (of the election) sincerely, but as for disaster response, the government as a whole is doing what needs to be done," he told a parliamentary panel.

Kan's critics in the DPJ were also expected to step up their attacks, but the party has no obvious successor in sight. Japanese media said the LDP was considering submitting a no-confidence motion against Kan in coming months - but more than 70 DPJ lawmakers would have to back the motion for it to pass.

"It is certain that Kan's clout has declined. It has become clear to the DPJ that they cannot fight the next general election under Kan," said independent analyst Minoru Morita.    

No general election is mandated until 2013, and the crisis has muted opposition calls for an early vote for parliament's powerful lower house.

"But while there are those (in the DPJ) who speak about a no-confidence vote, that would be very difficult," Morita added. "Unless Kan makes a fresh gaffe or a cabinet member quits ... it would be hard to move to that stage. So unless Kan resigns on his own, the situation will remain deadlocked."

Public opinion polls have shown that most Japanese want a new prime minister, but many would prefer Kan to stay until the crisis at Tokyo Electric Power Co's quake-crippled Fukushima Daiichi nuclear plant is resolved. When that will be is uncertain but it is likely to take many more months at least.