By Karolina Tagaris and Renee Maltezou
ATHENS (Reuters) - Greeks enraged by economic hardship voted on Sunday in a deeply uncertain election that could reignite Europe's debt crisis and throw into doubt the country's future in the euro zone.
At stake in the first general election since Greece detonated a wider European crisis at the end of 2009 is whether it will stick to the terms of a deeply unpopular EU/IMF bailout or start down a path that could take it out of the euro.
Leaders from all sides emphasised the importance of the vote for the future of Greece, which is suffering one of Europe's worst postwar recessions.
"We all agree that these elections are perhaps the most crucial and today each of us is deciding not only who will govern the country but also Greece's path for the next decades," said outgoing technocrat Prime Minister Lucas Papademos, as he cast his vote in Athens.
But many voters expressed their rage at the ruling parties.
"My vote was a protest vote because they cut my pension and there are more measures waiting for us around the corner," said 75-year-old pensioner Kalliopi, her fists clenched in anger.
"I live in a basement but pay the same (property) tax as someone who lives in a penthouse," said Kalliopi after voting in Athens.
Opinion polls indicate voters hit by record unemployment, collapsing businesses and steep wage cuts will return an unprecedented number of small parties opposed to austerity and punish conservative New Democracy and socialist PASOK, who have ruled for decades.
They are the only major parties backing bailouts that averted bankruptcy but caused grinding hardship.
The prospect that they will fail to win enough votes for a coalition government, despite finishing first and second, has raised the risk of a prolonged period of uncertainty as they seek allies from anti-bailout parties.
Papademos said he thought a new government could be formed this week.
International lenders and investors fear success for up to seven small parties opposed to the bailout could lead to Greece reneging on its bailout terms, risking a sovereign default and dragging the euro zone back into the worst crisis since its creation.
"WE ARE ALREADY BANKRUPT"
Euro zone paymaster Germany has warned there would be "consequences" to an anti-bailout vote and the EU and IMF insist whoever wins the election must stick to austerity if they want to receive the aid that keeps Greece afloat.
But many voters shrugged off such threats.
"I don't think that voting for a small party will make us go bankrupt. We already are," said 53 year-old Panagiotis, a craftsman, after voting for the conservative Independent Greeks.
At another polling station, 37-year-old computer technician Giannis Papadopoulos said: "I am outraged and I have been angry for 2-1/2 years. Today I voted for one of the small parties and the only thing I can tell them is please don't repeat the mistakes the others have made so far."
But some voters, like 60-year-old housewife Mary, saw the bailout as the only possible course.
"I voted for tough but necessary measures. I'm sorry to say it but their blackmail has worked in my case. What I expect is only disaster, there is no hope. I believe it can only get worse but at least we'll stay in Europe," she said.
PASOK leader Evangelos Venizelos said the vote was the most crucial since the end of a military dictatorship in 1974, but he was booed as he left a polling station in Greece's second city of Thessaloniki.
Alexis Tsipras, Greece's youngest political leader and head of the small Left Coalition, told reporters:
"We are certain that the people will send a message to all of Europe for a change of course. There is no place for the barbarity of bailouts in our common European path and we are certain that the Greek people will turn the page."
Polling stations opened at 7 a.m. (0400 GMT) and will close at 7 p.m., with many voters deciding at the last minute.
The first indication of the result is expected in exit polls immediately after voting stations close, but it could take many more hours to get the final outcome or even a clear picture under a complex electoral system that gives a 50-seat bonus to the first party.
TOO CLOSE TO CALL
Pollsters say this is the most unpredictable election in decades, as the traditional left-right divide gives way to pro- or anti-bailout supporters.
"All our tools are based on a society that does not exist anymore," said Costas Panagopoulos, at ALCO pollsters. "We cannot exclude any scenario."
The anti-bailout parties are too divided to rule together and even if New Democracy and PASOK scrape enough votes to renew a fractious coalition they set up in November to clinch a second, 130 billion euros bailout, the government could be too weak to weather public anger for long.
"The risk is high that after the elections, no stable coalition can be formed which would be willing to implement the next budget cuts and reforms," Berenberg Bank said in a note.
It said if Greece did renege on its commitments, it would probably have to leave the euro, something most Greeks oppose.
The acid test will come fast: the new government must next month get parliament to approve over 11 billion euros in extra spending cuts for 2013 and 2014 in exchange for more aid.
With an economy which is forecast to shrink by another five percent in 2012, that will be a tough task in a newly hostile parliament.
If no party wins outright, the president will give the biggest group - likely to be New Democracy - three days to form a government. If it fails, the next largest group gets a chance and so on down the line. If they all fail, new polls would be called in about three weeks.
The Greek ballot could well steal the limelight from the expected election of Socialist Francois Hollande as president in France, where anger over economic pain has also played a leading role.
"The wild card is Greece, and markets are starting to get nervous about it," said Sassan Ghahramani, CEO of New York-based hedge fund advisers SGH Macro. "We could see peripheral bonds and the euro pressured on Monday."
(Additional reporting by Ingrid Melander, Lefteris Papadimas, Dina Kyriakidou and George Georgiopoulos.; Writing by Barry Moody,; editing by Mike Peacock)
