Italians are going to the polls in two days of local elections seen as a test for the new coalition government.
The focus is on the Rome mayoral vote, where PM Enrico Letta's centre-left is fighting ex-PM Silvio Berlusconi's People of Freedom (PDL) party.
The PDL incumbent, Gianni Alemanno, is trailing Democratic Party (PD) candidate Ignazio Marino in the polls.
Elsewhere, 565 local authorities, including Ancona, Brescia, Pisa and Siena, are also holding elections.
The results are expected to show the relative popularities of the PDL and PD after they decided to form a grand coalition government to end two months of post-general election deadlock.
Beppe Grillo's anti-establishment Five Star Movement (M5S). which attracted a quarter of the vote in February's general election, did not back the coalition.
He is hoping to consolidate his claim to be Italy's biggest political force.
In Rome, Mayor Alemanno was trailing by two points in recent polls.
The former neo-fascist, who has been in power since 2008, has complained of suffering from a "disastrous legacy" from his left-wing predecessors, who governed the city for the previous 20 years.
He says he has put the public accounts "back in order", increased tourism and expelled 61,000 Roma.
Mr Marino, a former surgeon, says he will give the capital a more transparent system of financial management, accusing his opponent of hiding the scale of the administration's debt problems.
He has also promised to improve public transport and give 10,000 unemployed young people who enrol on job training courses a 500-euro (£425) monthly allowance.
The third major candidate is Marcello De Vito of Beppe Grillo's M5S.
If none of the 19 candidates in Rome wins more than 50% of the vote, the top two candidates will face a run-off on 9-10 June.
The polls close on Sunday at 22:00 (20:00 GMT) and re-open on Monday at 07:00 (05:00 GMT)