The Italian government on Monday decided to set 4 December as the date of a key referendum aimed at re-vamping Italy's political machinery and creating more stable governance.
Centre-left premier Matteo Renzi has staked his political credibility on the reforms, which aim to save money and simplify law-making by reducing the role of parliament's upper house Senate and reining in the powers of regional governments.
The reforms include turning the Senate into a leaner assembly of local-government representatives with limited powers and streamlining Italy's notoriously cumbersome legislative process.
The proposed reform package is the biggest shake-up of Italy's 60-year republican set-up but recent opinion polls suggest the outcome will be a close call.
Critics say that, coupled with an electoral law that grants election winners a safe majority in parliament, the constitutional reforms excessively strengthen the executive and undermine democratic checks and balances.
Opponents also claim the reform is badly written and will complicate, rather than making it easier to pass legislation
All opposition groups, the country's largest trade union and a minority of the ruling Democratic Party are against the Renzi-sponsored package.
Earlier on Monday, the head the Italian bishops conference, Cardinal Angelo Bagnasco, urged electors to weigh the choice they make in the referendum, warning its outcome would have "lasting consequences".
"We advise you inform yourselves on all the issues in order to be able to evaluate what is at stake and the lasting consequences," he said, opening an event in Rome.
The reforms have already been approved by parliament but Italy's constitution requires the government to put them to the electorate in a plebiscite.
