By Deepa Babington
ROME (Reuters) - Italians voted on Sunday in local election run-offs where Prime Minister Silvio Berlusconi's center-right coalition risks humiliating defeat in his home town of Milan for the first time in nearly 20 years.
Nearly 6 million voters are eligible to cast ballots in contests in 90 towns and six provinces, but the focus is squarely on the key battlegrounds of the financial capital Milan and the southern port of Naples.
Results are expected after voting ends on Monday.
Berlusconi took a drubbing in the first round of voting on May 15 and 16, when an uninspired center left managed to hold on to power easily in Turin and Bologna and forced the center right into run-offs in Naples and Milan, its northern power base.
Defeat in the run-offs, especially in Milan, would be a serious blow for Berlusconi, deepening divisions in the center right and potentially provoking challenges to his leadership.
"I'm hoping this vote will bring a change for Milan, an improvement," said salesman Bruno Pedrazzoli, 53, after casting his vote in Milan.
He complained of high pollution levels and insufficient public transportation in the city, where center-right mayor Letizia Moratti trailed with 41.6 percent of the first-round vote against leftist Giuliano Pisapia's 48 percent.
The media magnate characterized the vote as a referendum on his popularity, and was punished by voters in the first round for a series of sex scandals, corruption cases and a stagnant economy.
Days later, ratings agency Standard & Poor's lowered its outlook on Italy for failing to cut its debt mountain and boost growth.
"The Berlusconi era is ending," Walter Veltroni, a former center-left leader whom Berlusconi defeated in national elections in 2008, told the left-wing newspaper L'Unita.
Italy has weathered the financial crisis better than its southern European peers, but has been one of the euro zone's most sluggish economies for more than a decade.
Berlusconi's government last month was forced to cut its growth forecast for the year to 1.1 percent from 1.3 percent and cut next year's outlook to 1.3 percent from 2.0 percent.
Initially stunned into silence by the first-round results, Berlusconi has since taken to the campaign trail with a vengeance.
Blanketing the airwaves with tirades against his long-time enemies, the left and magistrates, he has predicted Milan will become an "Islamic gypsyland" if the left wins and accused leftist voters of lacking a brain.
A rant against Italian magistrates to a surprised U.S. President Barack Obama at the Group of Eight summit in Deauville, France prompted Economy Undersecretary Daniela Melchiorre, a former magistrate, to resign in protest.
Hours after the summit on Friday, Berlusconi flew to Naples for a flurry of television interviews and a duet with a Neapolitan singer to wrap up campaigning in trademark defiance.
Asked if the center right would face a crisis in the event of defeat, Berlusconi said: "I categorically exclude that."
A general atmosphere of acrimony marked the end of campaigning on Friday, with a fire sweeping through an election office for the center-right candidate in Naples and two people hurt in a brawl between supporters of rival candidates in Milan.
In Naples, a divided center left which fielded two candidates in the first round could fare better with a unified front in the run-offs, although both sides have taken flak for failing to resolve a chronic garbage crisis plaguing the city.
(Additional reporting by Valentina Za in Milan; Editing by David Cowell)