Greek voters will cast their ballots on Sunday in the country's first national election of the post-bailout era, with leftist Prime Minister's Syriza party expected to be ousted by the conservative opposition.

Iran Press/Europe: After nearly five years in power, Greece's longest-serving crisis premier -- as well as the youngest in more than a century -- is battling to overcome a 10-point deficit in opinion polls amid widespread dissatisfaction after years of high taxation.

As a trio of new opinion polls predicted a clear victory for the conservative New Democracy party, Alexis Tsipras has vowed that he can make "the biggest comeback in modern Greek history", AFP reported.

"The Greek people must not only vote, but they must also avert a theft of their sacrifices, a great crime against future generations," the 44-year-old premier told a crowd in Athens on Friday.

But the polls have consistently forecast that New Democracy headed by Kyriakos Mitsotakis, a former banker and scion of a leading Greek political family, will win an absolute majority in Sunday's legislative elections.

According to the latest polls, New Democracy is expected to gain between 151 to 165 seats in the 300-seat parliament. Syriza meanwhile is forecast to fall from 144 seats to between 70 and 82.

Snap election in Greece

Tsipras called the snap election in June after losing both European and local elections to Mitsotakis' New Democracy in the space of two weeks.

The Greek premier has also touted his party's track record in reducing unemployment and raising the minimum wage for the first time since 2012. But the majority of the electorate seems unmoved.

Tsipras has been widely criticized for campaigning as an anti-austerity crusader before eventually accepting a third EU bailout.

The vote will be Greece's third poll in as many months, and the country's first mid-summer general election since 1928 is unlikely to set participation records.

In May, fewer than 59 percent of registered voters cast ballots for European Parliament polls and the first round of local and regional elections. Participation fell below 42 percent for the second round a week later.

With temperatures forecast to go as high as 39 degrees Celsius (102 degrees Fahrenheit) on Sunday, all parties dread the impact the heat will have on turnout.

Syriza's number of seats in the next parliament is expected to depend on how many of the smaller parties secure at least three percent of the vote, the minimum required to enter parliament.

Polls show that each new party could win between nine and 10 MPs.  203/211/201

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