Italy's centre left voted on Sunday, November 25 to choose the candidate who will be the leading contender to succeed Mario Monti as prime minister after an election in March and take charge of steering the country through a deep recession, Reuters said.

Opinion surveys show Democratic Party leader Pier Luigi Bersani is the frontrunner among five candidates, followed by Florence mayor Matteo Renzi, who has vowed to shake up Italy's political establishment if he is chosen.

The vote will eliminate a major element of uncertainty before the election to choose a successor to Monti's technocrat government.

The centre-left alliance is well ahead in opinion polls for the parliamentary election and the winner of the primary vote is in pole position to take over Monti's efforts to control strained public finances and tackle a year-long recession.

Support for Prime Minister Silvio Berlusconi's deeply divided centre-right People of Freedom party (PDL) has crumbled to less than half than it recorded in the last election in 2008.

Berlusconi said on Saturday he was again thinking about running, deepening the PDL chaos.

Both Bersani and Renzi reject the idea, encouraged by international markets, that Monti should return after the vote to continue his economic policies that have so far included unpopular spending cuts, tax rises and labor reform.

Protests on Saturday by tens of thousands of students and workers from across the political spectrum highlighted the levels of discontent among Italians grappling with the slump and rising unemployment in the euro zone's third biggest economy.