The centre-left in recession-hit Italy voted Sunday to choose the Democratic Party candidate who will run for prime minister in a general election next year that it is widely expected to win.
The front-runners in a field of five are current PD leader Pier Luigi Bersani, a cigar-chomping ex-communist, and rising star Matteo Renzi, the youthful mayor of Florence who looks to US President Barack Obama for inspiration and has vowed to oust Italy's ageing political establishment.
The primary is being held at a time of deep economic crisis and political uncertainty in Italy, with a series of corruption scandals within the main parties sparking disgust with traditional leaders and voter apathy.
The Democratic Party is leading in opinion polls ahead of the April election, which will determine the successor to unelected technocrat Prime Minister Mario Monti, who took over from Silvio Berlusconi a year ago as Italy struggled with the eurozone crisis.
"We have to show the rest of the world that we don't just have Monti," Bersani, a former economic development minister, said last week.
"People want to take part, they want to have a politics that is in touch with the street, with the squares, that returns hope to the country," he said.
Monti's government pushed through austerity measures that have angered many Italians but spared the country a Greek-style collapse.
Finance Minister Vittorio Grilli said the economy would start to recover halfway through next year but warned that Italy was not yet in the clear.
"Even if the emergency phase was over, which it isn't, the markets wouldn't stop being on edge without the certainty that whoever is to govern in the future will continue on the path of rigour," he told La Stampa.
Bersani, 61, has said he wants to maintain the course set by Monti in terms of promoting "discipline and credibility" but do more to boost "employment and fairness" as Italy struggles through a painful recession.
Thousands of polling stations have been set up across Italy and 19 other countries with large Italian communities and Nicola Danti from Renzi's campaign said as many as 3.6 million people could turn out.
Initial results are not expected before 2130 GMT.
The three other candidates are Nichi Vendola, governor of the Apulia region, Antonio Tabacci, a former Christian-Democrat, and Laura Puppato, a regional lawmaker who has called for a "green economy".
A poll by the Cise/Luiss study centre on Thursday showed Bersani could win 48.2 percent -- 10 points ahead of Renzi with 37.6 percent, while Vendola was seen trailing far behind with 9.9 percent.
However, it also found that a leftist coalition led by the 37-year-old Renzi could come out on top. The research centre said Bersani represented "the soul of the identity of the left" while Renzi had "more transversal appeal".
Should none of the candidates manage to muster 50 percent plus one vote on Sunday, the primary will go into a second round on December 2.
Political analyst Roberto D'Alimonte, one of the founders of Cise, said Bersani was almost certain to win but that the turnout would prove crucial, since a sharp influx of new voters could favour the younger Renzi.
"If we win on Sunday, the Democrats have more of a chance of winning" at the general election, said Renzi, who has conducted a US-style campaign on a bus around Italy under the slogan: "Let's Change Italy Now!"
Berlusconi's once-dominant People of Freedom Party (PDL) -- which is bitterly divided by infighting -- will hold its own primary on December 16 to elect a centre-right candidate for the race for the premiership.
Berlusconi, the scandal-ridden three-time prime minister, has yet to make his own intentions clear.
"We'll see. I'm thinking it over," Berlusconi, 76, told reporters on Saturday when asked if he intended to return to politics.