Italian centre-left voters went to the polls on Sunday to choose the man likely to be prime minister after next year\'s general election in a race between Democratic Party leader Pier Luigi Bersani and Florence mayor Matteo Renzi. The winner of the second-round runoff will be the favourite to lead Italy\'s next government since opinion polls indicate the Democratic Party will win the election expected in March or April, although without an outright majority. The 61-year-old Bersani, a former communist party man, faces a challenge from the 37-year-old Renzi, a rising star who looks to US President Barack Obama and former British prime minister Tony Blair for inspiration. Both men have said that if they win the general election they would follow the broad course of reforms set by Prime Minister Mario Monti, who has pulled Italy back from the brink of bankruptcy during a year in government. Bersani however has said he would seek to moderate some of the austerity measures implemented by Monti, which have created growing resentment among many Italians against his unelected technocrat government. The primary selection process is seen as an important milestone for the left since the wave of support for Renzi could move the Democratic Party towards a more centrist political stance comparable to Britain\'s \"New Labour\". Sunday\'s winner will face a centre-right that has been steeped in crisis since Silvio Berlusconi resigned as prime minister in November 2011 following a wave of scandals. The party founded by Berlusconi, the People of Freedom, planned to organise its own primary vote on December 16 but this now appears to be in doubt. The 76-year-old Berlusconi, who has won three general elections in the past two decades, has left open the possibility he will run for premier once again. Bersani won 44.9 percent of the vote in the first round of the primary on November 25 in which 3.1 million people cast their ballots. Renzi came second with 35.5 percent -- a result that still impressed many observers. For his US-style campaign for the nomination, Renzi travelled across Italy in a camper van and held rallies under the slogan: \"Let\'s Change Italy Now!\" Bersani too is not taking victory for granted and has been touring the country to mobilise the electorate and to try to win over the people who voted for three other candidates in the first round. An opinion poll published Saturday by the IPR institute gave Bersani between 57.5 and 61.5 percent of the vote compared with 38.5 to 42.5 percent for his rival, but Renzi is seen as a \"transversal\" figure who can take votes from the centre-right come next year. In the run-up to the primary, Bersani has tried to spruce up his image by taking to social media and promoting women to senior posts on his team. The former minister has presented himself as a calming influence on a stormy political scene against Renzi, who has no experience in national government. The result hinges in large part on what supporters of first-round runner-up Nichi Vendola, who is seen as more of a leftist than either Bersani or Renzi, will do. Vendola has said he will vote for Bersani but has told the party leader that \"he still has to win the votes of my supporters\". He has been fiercely critical of Renzi, calling him \"a young man on the verge of nervous breakdown\". Preliminary results are expected later Sunday after polling stations close at 1900 GMT. The definitive outcome will be announced on Monday.