Media mogul Berlusconi campaigned for his center-right party's candidate in Rome, incumbent Gianni Alemanno, who is trying for a second term in a runoff against former transplant surgeon Ignazio Marino, who is backed by the center-left.
Alemanno trailed in the first round two weeks ago in Italy's capital. In his first run for the office, in 2008, Alemanno also trailed in the first round, but mounted a strong comeback to win in the runoff.
Rome is the only major metropolis at stake. Nearly all races are runoffs, except in the region of Sicily, which is holding its first round of mayoral elections. Voting ends tomorrow afternoon.
Beset by judicial woes, including a trial expected to yield a verdict later this month on charges that Berlusconi paid for sex with an underage teen and then tried to use his office while premier to cover it up, the 76-year-old billionaire businessman, who denies wrongdoing, tried for an electoral comeback in February parliamentary elections.
The largest vote-getter, the left-leaning Democratic Party, failed to win enough to control both houses of Parliament. After weeks of internal bickering, it was forced to ask Berlusconi's forces to help it form a coalition government.
The mayoral races will also be watched to see if the Democrats can project a winning image. Local electoral triumphs could help it to wield a stronger hand in the ruling coalition, which quickly gave in to Berlusconi's demands to stop an unpopular property tax. Payment of tax on primary residences has been suspended, while the government scrambles to find alternative revenues for lean state coffers.