Party secretary Pier Luigi Bersani is almost certain to win the Democratic Party’s primary election in Italy this weekend, but he will have to battle the charismatic mayor of Florence Min a second round if he fails to win more than half of the votes.

More than three million Italians are expected to take part in the first voting round on Sunday.

The Democrats are the largest left-wing party in parliament and have supported Mario Monti’s economic reforms since he replaced Silvio Berlusconi as prime minister late last year.

Italy’s next prime minister

Bersani, a former communist who served as minister for economic development in the country’s last left-wing government, led in a Tecne exit poll with 47 percent support against 30 percent for his rival, Matteo Renzi.

But according to a study published in Il Sole 24 Ore, Renzi could win 44 percent of the votes in a general election against 35 percent for the presumptive nominee.

With Berlusconi’s conservatives down in the polls and Monti set to step down next year, the left has a clear opportunity to win back the prime ministership and lead the next government.

Bersani, a party apparatchik, is seen by moderates as too left of center. Renzi, who has embraced labor-market reform and proposed a comprehensive overhaul of the Italian voting system, appeals to the electorate at large but is seen as too liberal by Democratic Party insiders.

Polls

The right is due to hold its own primary in December, although Party Secretary Angelino Alfano has told reporters elections would make little sense if Berlusconi sought the nomination again.

The former prime minister, despite being embroiled in corruption and sex scandals, is considering a comeback.

Parliamentary elections are due in April. An Ipsos poll that released on Thursday put support for Berlusconi’s party at 15 percent compared to 32 percent for the Democrats.

Comedian Beppe Grillo’s Euroskeptic Five Star Movement gets 20 percent in the Ipsos poll, which would make it the second largest party.