As Greece heads for a momentous electoral battle on Sunday that could determine its place in the eurozone, party leaders are mustering their forces and presenting voters with a stark choice. In the right corner, the conservative New Democracy party headed by 61-year-old economist Antonis Samaras, seen by European leaders as Greece\'s best hope to continue structural reforms tied to its EU-IMF loan rescue. In the left corner, the radical leftist Syriza party, whose 37-year-old leader Alexis Tsipras has pledged to tear up the bailout deal after the vote, and which scored a shock second place in Greece\'s last election on May 6. \"The bailout deal is already in the past. It will be history for good on Monday,\" Tsipras has said -- in defiance of multiple warnings from European leaders that rejecting the deal will also end loans vital for the Greek economy. In a commentary in the Financial Times on Wednesday, Tsipras said his party was \"committed to keeping Greece in the eurozone\" and warned that the current line of austerity could \"force us out of the euro with even greater certainty.\" Riding a wave of anger from an electorate fed up with over two years of austerity cuts, Syriza more than tripled its score from 2009 elections in a vote last month that proved inconclusive and triggered Sunday\'s election. Crowds of volunteers have been handing out leaflets in the streets and posters are going up all around with Syriza promising to \"Open the Way for Hope\" and Socialist PASOK, the third party, saying: \"Greeks fight and will succeed.\" \"We move forward with responsibility and determination,\" reads a slogan from New Democracy written on a wall near the main pavilion in central Athens. According to opinion polls, Syriza\'s race with New Democracy will come down to the wire -- with the campaign all the more heated as a top spot would secure a key advantage by giving the winner an extra 50 seats in parliament. Alarmed by the previous election round, which saw them hold off Syriza by less than three percent, the conservatives are trying to piece together a \"European patriotic front\" and have cast a wide net across the political divide. On May 21, ND chief Samaras buried the hatchet with old foe Dora Bakoyannis and absorbed her small liberal party Democratic Alliance, which had picked up 2.56 percent of the vote on May 6 but failed to enter parliament. In parallel, Samaras has also poached several prominent lawmakers from the nationalist party Laos, including a former far-right youth leader who served as transport minister in the recent Greek coalition government. And in a move that has raised eyebrows, the party recently entrusted its northern Greece campaign to the disgraced but popular prefect of Thessaloniki, who was suspended from his duties last year for interfering with justice. \"The European patriotic front is constantly growing,\" Samaras said earlier, after a new crop of Laos deputies joined his party. \"Together we will give the big battle to change the loan agreement policies and keep Greece standing in Europe,\" he said. Syriza has not been idle either, enlisting two socialist deputies -- one of them Greek javelin legend Sofia Sakorafa -- who later dominated electoral lists in the greater Athens region with over 53,000 votes each. A number of ex-socialist senior trade unionists angered by civil service cuts have also flocked to Syriza, which has promised to reverse onerous labour reforms demanded by the EU and the IMF in return for rescue loans. And the leftists also signed up Louka Katseli, an ex-OECD official and socialist economy minister who was ejected from her party for opposing Greece\'s second bailout agreement with the eurozone and the International Monetary Fund. Amid widespread voter anger and apathy, pollsters have struggled to predict a clear winner in recent weeks. Polls in mid-May had forecast a Syriza victory. The pendulum then briefly swung back to New Democracy, with surveys predicting a conservative victory ranging between 23.3 percent and 25.8 percent. Since then, the lead has changed hands almost on a daily basis. The final surveys allowed before the election showed New Democracy\'s vote ranging from 25.5 to 26.5 percent, and Syriza\'s from 23.5 to 31.5 percent. With neither party likely to secure an overall majority, the post-election period is almost certain to be dominated by frantic coalition negotiations.