Here is a look at the main parties and candidates running:
The Athens-born civil engineer is a veteran of Greek politics at age 44, leading the once-marginal Coalition of the Radical Left, Syriza, to a landmark election victory in 2015.
Politically active since his teenage years, Tsipras rose to power as Greece's economy was plunged into financial crisis and voters turned their backs on traditionally dominant parties. Tsipras was first elected on a promise to scrap the draconian terms imposed for bailouts by European Union institutions and the International Monetary Fund,
But he was forced to accept a third rescue deal to keep Greece in the euro. He has since dropped a confrontational stance toward Germany and other large creditor nations and has also built closer military ties with the United States.
Praised by Western allies, his government also hammered out a historic compromise with Balkan neighbor North Macedonia, in a name-change deal that remains broadly unpopular among Greeks.
Tsipras has promised to rebuild public services after years of hardship and funding cuts and insists his party can overturn a huge gap in opinion polls.
Despite facing skepticism within his own party, the 51-year-old Mitsotakis has built a huge lead in opinion polls spanning back three years and is the strong favorite to win Sunday.
A tireless campaigner, Mitsotakis is the Harvard-educated son of the late prime minister Constantine Mitsotakis whose combative style as conservative leader in the late 1980s and early 1990s still remains controversial.
The younger Mitsotakis, leader of Greece's conservative establishment party since January 2016, has struggled to shed an image of family privilege. He focused his campaign on blue collar voters and pledged to make the country more-business friendly, cut taxes, and modernize Greece's antiquated bureaucracy.
Mitsotakis served in a previous conservative government as minister of administrative reform. Unlike many other conservative leaders in the EU, he remains a staunch supporter of deeper European integration. He disputes claims by the Tsipras government that he is tied to the rightist wing of his party and favors privatizing welfare services.
Currently polling in third place, the 54-year-old Gennimata is leader of the Movement for Change, a rebranded Pan-Hellenic Socialist Movement, or Pasok, the party that dominated the government for three decades but was devastated by the financial crisis a decade ago and has lost the bulk of its support to Prime Minister Tsipras' Syriza party.
An effort two years ago by Gennimata to expand the party, joining forces with other centrist groups, was tarnished by multiple policy and administrative disputes within the revamped party. Gennimata has overtaken the extreme right Golden Dawn Party for third place in opinion polls before Sunday's election.
The former director of a Communist newspaper, Dimitris Koutsoumbas, 63, is the General Secretary of the Communist Party of Greece, KKE, a party that maintained unwavering support for the Soviet Union's leadership over decades while other Communist parties in Europe distanced themselves from Moscow.
Koutsoumbas has defended party political traditions and orthodoxy, focusing attacks on its one-time ally Syriza, accusing it of selling out workers' rights. The KKE's leadership failed to win over any significant boost in public support for the party during the financial crisis and has seen its share of the vote dip over the last 20 years.
Three other parties are vying for seats in parliament — set by a threshold of 3% of the vote nationwide.
Golden Dawn is an extreme right party founded by neo-Nazi supporters 34 years ago, and leaders currently face charges related to incitement to violence. The party suffered a sharp drop in support before Sunday's vote.
Former Finance Minister Yanis Varoufakis founded a pan-European anti-austerity party in 2016 and narrowly missed the threshold in Greece in European Parliament elections in May.
And far-right TV pundit Kyriakos Velopoulos and his party Greek Solution has seen a surge in support in recent months.
Full AP coverage of Greece at https://www.apnews.com/Greece