Update at 3 p.m. ET
Supporters of former Prime Minister Alexis Tsipras' Syriza party cheered and waved flags in the capital after the leftist party won a convincing victory over the conservative New Democracy party in snap elections.
With 44 percent of the ballots counted, Syriza was polling 35.5 percent of the vote, compared to just 28 percent for New Democracy. A Nazi-inspired party, Golden Dawn, trailed with 7.1 percent.
Tsipras had called the election after his government negotiated a $96 billion bailout deal with the European Union that was rejected in a nationwide referendum. The prime minister — whose party won in January on a pledge to oppose austerity measures demanded by the European Union as a condition of bailing out the country's teetering economy — decided to ignore the referendum and agree to the deal anyway.
New Democracy, led by Vangelis Meimarakis, who had promised that if his party is voted in it would banish "greyness, falsehoods and misery ... and bring in authentic people for a better tomorrow for all Greeks," conceded defeat.
"The election result appears to be forming comprehensively with Syriza and Mr. Tsipras coming first," Meimarakis said. "I congratulate him and call on him to form the government that is necessary, and bring the (proposal) to parliament."
Even so, turnout appears to have been low amid a sense of disillusionment at the prospects.
"What we are hoping for is for the less useless (politician) so he does the least damage to Greece," 77-year-old Yiannis told Reuters outside a polling station in Athens.