By Gavin Jones
ROME (Reuters) - Italians are electing municipal mayors on Sunday in a test of parties' support ahead of a parliamentary election to be held by next spring at the latest.
Some 9 million voters will elect mayors in more than 1,000 towns and cities, with runoffs to be held on June 25 where no candidate gets more than 50 percent in the first round.
The political climate ahead of the vote became even more hostile this week after a deal on electoral reform among the main parties broke down in parliament amid bitter recriminations.
The collapse of that accord seems to have reduced the chances of a snap election in the autumn, but the coalition backing Prime Minister Paolo Gentiloni is fragile and analysts say an early vote still cannot be ruled out.
Although Sunday's vote will be one of the last before the general election, local factors mean it may not provide a clear reflection of the parties' national standings.
Moreover, in many of the contests, the parties have taken a back seat and chosen to camouflage themselves in broad "civic list" coalitions rather than present their own individual candidates.
The largest city at stake is Palermo, where incumbent mayor Leoluca Orlando, a veteran anti-mafia campaigner backed by Italy's ruling Democratic Party (PD) and other centre-left groups, is expected to see off his rivals from the center-right and the anti-establishment 5-Star Movement.
A closer contest is expected in the northern port city of Genoa, where the center-right hopes to win control from the incumbent center-left. The city is home to 5-Star's founder, comedian Beppe Grillo, but the movement's prospects there have dwindled due to a local internal split.
The center-right, dominated by the Northern League and Silvio Berlusconi's Forza Italia party, is favorite in Verona in the northeast, while the center-left is expected to keep control of L'Aquila, capital of the central Abruzzo region.
5-Star is running neck-and-neck with the PD nationally, according to opinion polls, but it often struggles in local elections due to its loose organization and lack of high-profile candidates, and it is expected to score few successes on Sunday.
In the northern city of Parma, its first ever mayor, elected in 2012, is running as an independent after falling out with the party leadership last year, and is favorite to win against rivals from the center-right and center-left as well as 5-Star.
Exit polls will be published for the main cities when polls close at 11 p.m. (2100 GMT) and first projections based on the actual vote count will be released about 45 minutes later.
(Reporting by Gavin Jones; Editing by Kevin Liffey)