Greece’s snap parliamentary elections on Sunday could bring to power Europe’s first radical leftist government, polls have shown.

The leftist anti-austerity party SYRIZA has widened its election lead, which is putting it on course for defeating the conservative New Democracy party of Prime Minister Antonis Samaras, the dominant force in a coalition government with Socialist party PASOK that has held power since June 2012.

A poll released by pollster GPO on Thursday gave SYRIZA a six-percentage-point lead over New Democracy. A week earlier, GPO had the lead at four percentage points.

According to an Alco poll released on Friday, Syriza has 32.9% support, giving it a 6.6 point lead - up from 5.2 points in a survey by the same pollster on Wednesday. Surveys by Kapa Research and MRB for Star TV put the difference between the two parties at 2.9 and 5.2 points, respectively. About 10% of those polled were undecided.

Under Greece’s election rules, a political party generally needs to win between 36% and 40% of the vote to secure a majority in the 300-seat one-chamber parliament.To enter parliament, a party needs a minimum of 3% of the vote. 

MPs are elected through a combined system of majority and proportional representation. The winning party is rewarded with a 50-seat bonus but needs 151 seats to form a majority.

According to analysts, SYRIZA will find it difficult to win outright majority amidst growing pressure from the EU and IMF to respect Grece’s commitment to austerity measures made in exchange for the EUR 240B bailout programme of the so-called troika – the EU, the International Monetary Fund (IMF) and the European Central Bank (ECB).

Media speculation has it that SYRIZA, or Coalition of the Radical Left, might prefer to enter a coalition government that would enable it to continue the structural reforms and budget cuts demanded by the international lenders.

To Potami, a new centrist party, has been widely seen as a potential ally of SYRIZA.

PASOK also could be an ally after Socialist leader Evangelos Venizelos told Reuters earlier this week the party could support a government led by SYRIZA as part of a wider pro-euro alliance to steer Greece out of its bailout programme.

According to opinion polls, the anti-bailout Independent Greeks party has emerged as a potential coalition partner for SYRIZA. Since 15 January, 16 of 18 opinion polls have given the partythe minimum of 3% needed to enter parliament. 

Although it is centre-right party formed by rebels from New Democracy, the Independent Greeks share Syriza's opposition to the terms of the bailout programme.

SYRIZA leader Alexis Tsipras, who has declared his intention to renegotiate and write off part of Greece’s massive debt and cancel the austerity measures, said on Thursday his party would restore "dignity" to the country. Greece’s debt totalled EUR 320B last year, almost EUR 30,000 per resident.

“History is knocking at our door,” he told thousands of cheering supporters in Athens on Thursday, appealing to all Greeks to vote to overthrow an establishment widely blamed for bringing the country to the point of economic and social collapse.

Greeks saw their income considerably reduced by heavy taxation and slashing of wages and pensions in recent years. The economy has shrunk by a quarter in less than five years – a rate of decline unseen in the modern era. Unemployment rate remains around 26% and almost three in every five young Greeks is jobless.

The possibility of a SYRIZA vote has sparked fears that Greece could default on its debt and exit the eurozone.

Unlike Tsipras, Prime Minister Antonis Samaras has called on the Greek voters to "stay the course", pledging to take Greece out of the bailout programme early albeit with an extended line of credit.

Samaras has also said that that following years of austerity, Greece is now showing signs of recovery. Revenue from tourism is increasing, the government budget is showing a surplus and the country is no longer in recession.