TOKYO: Campaigning began Tuesday for one of the most hotly contested elections Japan has seen in more than a decade and a major poll said the party that has run the country for most of the past 55 years is lagging well behind the opposition.

The elections for the lower house of parliament, to be held Aug. 30, are seen as one of the biggest tests Japan's ruling Liberal Democratic Party has ever faced. If forecasts are correct, it could cost them their control over the government and lead to the selection of a new prime minister.

The Liberal Democrats have governed Japan alone or in a coalition arrangement for all of the past 55 years except for a brief respite in the early 1990s.

"Our party has been right in its economic policies," Prime Minister Taro Aso said in his kickoff speech. "We will press ahead. We are not finished with our efforts to see economic recovery. Recovery is our foremost priority."

But a poll in the Asahi newspaper, a major daily, said the party has only 21 percent support among voters, compared with 40 percent who say they will opt for the opposition Democratic Party of Japan.

The ruling party has been plunging in support because of the weak economy, increasing unemployment, a perceived lack of leadership and its support of higher taxes. Its leader, Aso, is also deeply unpopular for his failure to lead the country out of its troubles and his tendency to make embarrassing gaffes.

Aso's support rating was 19 percent in the Asahi poll, while his disapproval rating was 65 percent.

The Asahi poll of 1,011 voters was in line with other recent polls by major media. A poll of that size would normally have a margin of error of about 5 percentage points.

Aso and opposition leader Yukio Hatoyama have squared off twice in televised debates ahead of the official start of campaigning.

Aso has stressed that his party has delivered results and built up the country from the ashes of defeat in World War II in 1945, while alleging that the opposition is making promises of public spending and social programs that it cannot pay for.

Hatoyama, meanwhile, has said Japan needs a change of government to get itself out of its current morass, that it must cut wasteful spending and rein in the power of bureaucrats, who have broad authority over setting budgets and formulating laws.

"The day has come to change the history of Japan," Hatoyama said on a stumping tour. "Let's step into a new era with courage."

Being contested are the 480 seats in the lower house, the more powerful chamber of Japan's bicameral parliament. Going into the elections, the Liberal Democrats had 302 seats, and the Democratic Party had 112. This will be the first election for the chamber since September 2005.

The party that controls the lower house has the power to install the prime minister.