Greece's Socialists trounced the governing conservatives in a landslide election on Sunday, with voters angered by scandals and a faltering economy ousting Prime Minister Costas Karamanlis halfway through his second term.

Humbled by his New Democracy party's worst electoral performance ever, Karamanlis, 53, resigned as its leader and said a new chief is needed for the party founded by his late uncle Constantine Karamanlis 35 years ago.

George Papandreou, 57, now follows in the footsteps of his father, Andreas Papandreou, who founded his Panhellenic Socialist Movement party, or PASOK, and grandfather and namesake George Papandreou, both of whom served several terms as prime ministers.

``We bear a great responsibility to change the course of the country. ... We know that we can make it,'' Papandreou, a former foreign minister, told jubilant supporters lighting flares and waving PASOK flags depicting the party's symbol of a green rising sun outside his party headquarters in central Athens.

Results from 60.67 percent of votes counted showed PASOK winning with 43.72 percent, compared to 34.74 percent for New Democracy.

The result gives PASOK a comfortable majority of about 159 seats in the 300-member parliament, bringing the party back to power after five years of conservative governance.

Papandreou's victory, along with a recent election win by socialists in Portugal, bucks a European trend that has seen a conservative surge in the continent's powerhouse economies, including most recently in Germany, where Chancellor Angela Merkel won re-election last week.

``This is a historic victory for PASOK, which means great responsibility for us,'' senior party official and former minister Evangelos Venizelos said.

Papandreou will now have to deal with a faltering economy that is expected to contract in 2009 after years of strong growth, while the budget deficit will probably exceed 6 percent of economic output.

In contrast to Karamanlis, who advocated an austerity program of freezing state salaries, pensions and hiring, Papandreou has promised to inject up to euro3 billion ($4.4 billion) to jump-start the economy.

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