Italians voted Sunday in the second round of municipal polls in 67 towns and cities, with Rome's right-wing mayor Gianni Alemanno facing a stiff challenge from the centre-left candidate.
Little known on the national scene, challenger Ignazio Marino picked up 43 percent of the vote in the first round two weeks ago, while Alemanno, a former neo-fascist, came in second with 30 percent.
Victory for Marino would be a shot in the arm for the centre-left Democratic Party (PD), which lost ground in this year's inconclusive general elections, while Silvio Berlusconi's centre-right People of Freedom Party (PDL) has fared poorly in previous recent municipal votes.
"I have the full support of the PDL, and Silvio Berlusconi has entered the ring using his preferred means, which is television," Alemanno said winning the endorsement of the media baron and former prime minister.
"The whole party is working to win this election," he said. "Everyone knows that we can't leave Rome to Mr Marino. The future of the right depends on my victory."
The two-day vote ends Monday at 1300 GMT, with results expected in the evening.
Marcello De Vito, the candidate of the Five Star Movement of populist firebrand Beppe Grillo, did not back either candidate after scoring just 12 percent in the first round, but the party tends to sympathise with the left.
Independent candidate Alfio Marchini, who came last in the first round with 9.5 percent, also did not indicate his preference, although he has been openly critical of Alemanno.
The first-round vote in 563 towns and cities saw a record low turnout, reflecting Italians' disaffection with politics.