Greek voters head to the polls again Sunday in an election where conservative front-runner Kyriakos Mitsotakis is seeking a second term and an absolute parliamentary majority to form a "stable government."

Polling stations opened for the second round of general elections in five weeks at 7 am while the first exit polls are expected at 7 pm when polls close.

The 55-year-old Harvard graduate, who steered Greece from the coronavirus pandemic back to two consecutive years of strong growth, had already scored a thumping win in an election just a month ago.

But having fallen short of five seats in parliament to be able to form a single-party government, Mitsotakis chose to ask 9.8 million Greek voters back to the ballot boxes.

Mitsotakis, who hails from one of Greece's most influential political families, had trounced his next nearest rival, former leftist prime minister Alexis Tsipras, by more than 20 percentage points in the last vote.

As election rules this time round would accord up to 50 bonus seats to the winner of the vote, Mitsotakis's New Democracy party is widely projected to emerge victorious.

The main danger facing him would be a larger no-show rate at the polls because of the perceived foregone outcome.

Urging his supporters to turn up at the polls, he has warned of the possibility of a third election if he fails to get a majority.

"I hope we don't have to meet again in early August," he told Skai TV hours before a campaigning blackout began Saturday, adding that "this is no joke".

"All the gains we have made must be consolidated and continued," he said.