By Linda Sieg
TOKYO (Reuters) - Only one in five Japanese voters backs Prime Minister Taro Aso's government, polls showed on Monday, a tumble in popularity that erodes his clout with his fractious party as he struggles with an economy in recession.
The surveys cast fresh doubt on Aso's ability to control policy decisions and keep his job, or even to prevent the long-ruling Liberal Democratic Party (LDP) from unravelling ahead of a general election that must be held by next September.
Aso is Japan's third premier to be installed since the last general election in 2005, when the ruling bloc won a huge majority in parliament's powerful lower house.
His predecessors, Shinzo Abe and Yasuo Fukuda, both quit after about a year in office after policy missteps and a deadlocked parliament caused their support rates to tumble below 30 percent, a level seen by analysts as vital for survival.
"I think there will be more overt attempts to get rid of him, but given that they have done that three times without an election, the LDP is going to tear itself apart," said Koichi Nakano, a political science professor at Sophia University in Tokyo.
The LDP tapped Aso, an outspoken nationalist, in September in hopes he could win the ruling bloc a mandate to break through the political deadlock born of a divided parliament that is stalling policies as the recession deepens.
But Aso's early ratings were only around 50 percent and his support has slid ever since due to policy flip-flops and gaffes, prompting him to put off calling a snap election.
Some analysts say the opposition Democratic Party, a mix of former LDP members, one-time socialists and conservative younger lawmakers, has a good shot at taking power for the first time.
A survey by the Yomiuri newspaper showed Aso's support falling by about half to 21 percent, while the Mainichi newspaper showed a drop of 15 points to the same level. Another poll by the Asahi newspaper put his support at 22 percent.
"The people have completely given up on him," said Yukio Hatoyama, secretary-general of the Democratic Party.
But with no obvious successor in the LDP to take Aso's place, some analysts said he could hang on until after the national budget for the year from April 1 is enacted in late March.
OPPOSITION DEMOCRATS BENEFIT
Aso's declining support has undermined his control over the LDP, with many pushing for heftier spending to prop up the floundering economy despite huge public debt.
Others such as former financial services minister Yoshimi Watanabe are hinting at leaving to form new parties in hopes of bettering their chances in the looming election.
Another group could coalesce around former defence minister Yuriko Koike, who ran against Aso for the premiership under a reform banner, and her backer Hidenao Nakagawa, a former LDP secretary-general.
"The battle will begin in January," said Keio University professor Yasunori Sone. "No one wants to fight an election under Aso, but we cannot see who would replace him."
Independent political commentator Minoru Morita, however, was sceptical whether Watanabe and others would really jump ship.
"They don't have the clout to set up new parties," he said.
Chief Cabinet Secretary Takeo Kawamura, meanwhile, rejected talk of a change at the top. "One should not change the horse when passing through a strong current, and we are not in a situation where we can change horses," he told reporters.
The media surveys also showed the Democrats taking a clear lead among the electorate, with 40 percent in the Yomiuri poll opting for the main opposition party against 24 percent for the LDP when asked for whom they would vote in the next election.
Democratic Party leader Ichiro Ozawa, a former LDP heavyweight who bolted the party in 1993 and helped briefly oust it from power, has also gained from Aso's decline.
Ozawa, 66, suffers from an autocratic image and has lagged Aso in polls, but he led in all three new surveys when voters were asked which of the two was most suitable to run the country.
Still, many voters appear dissatisfied with both main parties, whose squabbling in a divided parliament is making it hard to implement policies as the economy stumbles.
Nearly 60 percent of voters in the Yomiuri poll said they wanted a rejig of political parties after the election or a "grand coalition" between LDP and the Democrats.
The Yomiuri survey was conducted over the phone on Friday, Saturday and Sunday, while the Mainichi and Asahi surveys were conducted over the phone at the weekend.
(Additional reporting by Yoko Kubota; Editing by Rodney Joyce)