Japan's ruling party conceded a crushing defeat Sunday after 54 years of nearly unbroken rule as voters were poised to hand the opposition a landslide victory in nationwide elections, driven by economic anxiety and a powerful desire for change. The left-of-center Democratic Party of Japan was set to win 300 or more of the 480 seats in the lower house of parliament, ousting the Liberal Democrats, who have governed Japan for all but 11 months since 1955, according to exit polls by all major Japanese TV networks. "These results are very severe," Prime Minister Taro Aso said in a news conference at party headquarters, conceding his party was headed for a big loss. "There has been a deep dissatisfaction with our party." Aso said he would have to accept responsibility for the results, suggesting that he would resign as party president. Other LDP leaders also said they would step down, though official results were not to be released until early Monday morning. The loss by the Liberal Democrats - traditionally a pro-business, conservative party - would open the way for the Democratic Party, headed by Yukio Hatoyama, to replace Aso and establish a new Cabinet, possibly within the next few weeks. The vote was seen as a barometer of frustrations over Japan's worst economic slump since World War II and a loss of confidence in the ruling Liberal Democrats' ability to tackle tough problems such as the rising national debt and rapidly aging population. The Democrats have embraced a more populist platform, promising handouts for families with children and farmers and a higher minimum wage. "The nation is very angry with the ruling party, and we are grateful for their deep support," Hatoyama said after the polls closed. "We will not be arrogant and we will listen to the people." The Democrats have also said they will seek a more independent relationship with Washington, while forging closer ties with Japan's Asian neighbors, including China. But Hatoyama, who holds a doctorate in engineering from Stanford University, insists he will not seek dramatic change in Japan's foreign policy, saying the U.S.-Japan alliance would "continue to be the cornerstone of Japanese diplomatic policy." National broadcaster NHK, using projections based on exit polls of roughly 400,000 voters, said the Democratic Party was set to win 300 seats and the Liberal Democrats only about 100. TV Asahi, another major network, said the Democratic Party would win 315 seats, up from the 112 seats it held before parliament was dissolved in July. As voting closed Sunday night, officials said turnout was high, despite an approaching typhoon, indicating the intense level of public interest in the hotly contested campaigns. "We've worked so hard to achieve a leadership change and that has now become almost certain thanks to the support of many voters," said Yoshihiko Noda, a senior member of the DPJ. "We feel a strong sense of responsibility to achieve each of our campaign promises." Even before the vote was over, the Democrats pounded the ruling party for driving the country into a ditch. Japan's unemployment has spiked to record 5.7 percent while deflation has intensified and families have cut spending because they are insecure about the future. Making the situation more dire is Japan's aging demographic - which means more people are on pensions and there is a shrinking pool of taxpayers to support them and other government programs. "The ruling party has betrayed the people over the past four years, driving the economy to the edge of a cliff, building up more than 6 trillion yen ($64.1 billion) in public debt, wasting money, ruining our social security net and widening the gap between the rich and poor," the Democratic Party said in a statement as voting began Sunday. "We will change Japan," it said. The Democratic Party would only need to win a simple majority of 241 seats in the lower house to assure that it can name the next prime minister. The 300-plus level would allow it and its two smaller allies the two-thirds majority they need in the lower house to pass bills. Many voters said that although the Democrats are largely untested in power and doubts remain about whether they will be able to deliver on their promises, the country needs a change. "We don't know if the Democrats can really make a difference, but we want to give them a chance," Junko Shinoda, 59, a government employee, said after voting at a crowded polling center in downtown Tokyo. Having the Democrats in power would smooth policy debates in parliament, which has been deadlocked since the Democrats and their allies took over the less powerful upper house in 2007. With only two weeks of official campaigning that focused mainly on broadstroke appeals rather than specific policies, many analysts said the elections were not so much about issues as voters' general desire for something new after more than a half century under the Liberal Democrats. The Democrats are proposing toll-free highways, free high schools, income support for farmers, monthly allowances for job seekers in training, a higher minimum wage and tax cuts. The estimated bill comes to 16.8 trillion yen ($179 billion) if fully implemented starting in fiscal year 2013. Aso - whose own support ratings have sagged to a dismal 20 percent - repeatedly stressed his party led Japan's rise from the ashes of World War II into one of the world's biggest economic powers and are best equipped to get it out of its current morass. In the end, voter worries about the economy and disenchantment with the LDP's long grip on power proved too much to overcome. "It's revolutionary," said Tomoaki Iwai, a political science professor at Tokyo's Nihon University. "It's the first real change of government" Japan has had in six decades.