The two parties have ruled Greece for many years, and analysts anticipate neither one will enjoy strong support among the country's voters, who are angry about the austerity imposed on them because of the terms of the bailouts dictated by the so-called troika: the European Central Bank, European Union, and International Monetary Fund.
Greece has about 9.9 million registered voters, according to the International Foundation for Electoral Systems' ElectionGuide.
Polls will open at 7 a.m. local time (Saturday at midnight EDT) and close at 7 p.m. local time (Sunday at noon EDT).
Many Greeks hope pressure from the troika may be relaxed in the event of a victory for French presidential candidate Francois Hollande, who has voiced skepticism over austerity, according to the BBC's Mark Lowen. France is conducting its own presidential election on Sunday.
In Greece, voters hit by record unemployment and steep wage cuts will send to parliament an unprecedented number of small parties opposed to austerity as they punish the New Democracy and Pasok parties for backing the bailouts, Reuters forecast based on its reporting.
The big parties are saying that if we don't vote for them we may be forced out of the euro. I am not sure that's the case. The two big parties have been in power too long, it's time for change, there has been too much austerity and scandals, Helen Theohari, a 37-year-old who is unemployed, told Reuters.
Pollsters believe it is impossible to say who undecided voters will choose as the old left-right divide has given way to a new pro-bailout/anti-bailout schism.
All our tools are based on a society that does not exist anymore, Costas Panagopoulos at ALCO pollsters told Reuters. We cannot exclude any scenario.