Prime Minister Silvio Berlusconi faced a possible second blow in the wake of his defeat in local elections, as Italians flocked to the polls on Sunday to vote in opposition-sponsored referendums.
The government has urged its supporters to stay away but turnout was already at 41 percent on Sunday and voting continues on Monday - indicating that the 50 percent needed for the polls to have legal validity was within reach.
It is widely assumed that the referendum questions against a return to nuclear power and a law granting Berlusconi a form of legal immunity will be approved since many of those taking part are opposition supporters.
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The success of the vote is therefore likely to hinge on the turnout.
The nuclear referendum would put a definitive stop to government plans to re-start Italy's atomic energy programme by 2014, which are already under a temporary moratorium following the Fukushima disaster in Japan.
Voters could also quash a law, approved last year, allowing Berlusconi to skip court appearances because of official obligations.
The prime minister, 74, is a defendant in three trials involving allegations of having paid for sex with a 17-year-old girl, as well as bribery and fraud.
A Constitutional Court ruling has already curbed much of Berlusconi's legal protection but the "legitimate impediment" law is still officially in place.
"If we manage to meet the quorum on legitimate impediment it will show that people have turned against the Berlusconi system," Margherita Lodoli, 28, a charity worker in Rome, told AFP after casting her ballots.
"Unfortunately he'll carry on, he always does, but it will prepare the ground for the next election," she added.
TIME FOR A RETHINK?
Commentators said the success of the referendums would force a fundamental rethink within Berlusconi's ruling coalition.
"It's clear that a wave of 'yes' votes will give a shock -- maybe a final one -- to his premiership and then also to the leadership of the PDL," the ruling People of Freedom party, business daily Il Sole 24 Ore said.
The leftist La Repubblica daily said Berlusconi was unlikely to resign if the referendums go against him but added that they could trigger an "implosion" of the People of Freedom and its coalition partner, the Northern League.
There is already infighting within Berlusconi's party following its defeat in mayoral elections in Milan and Naples last month -- with many supporters complaining that the prime minister has lost his campaigning touch.
Il Giornale, a newspaper owned by the Berlusconi family, however warned against interpreting the result of the referendums too much.
"Attributing to the referendums a value that goes beyond what the questions being asked are is an abuse, it's a dirty game," the newspaper added.
Polling stations are set to re-open at 7:00 am (0500 GMT) on Monday and close at 3:00 pm. The final result is expected later on Monday.
The nuclear issue has been at the centre of heated debates in recent weeks.
Italy abandoned atomic energy with a referendum in 1987 after the Chernobyl disaster but Berlusconi has made its re-introduction a major policy goal.
The government argues that nuclear power would slash electricity bills, reduce Italy's energy dependency and be better for the environment.
Opinion polls show however that nuclear power remains deeply unpopular.
Daniel Cohn-Bendit, leader of the Greens in the European Parliament, has said that a vote against nuclear power in Italy "could open a serious phase of reflection in other member states" of the European Union.
Apart from nuclear power and the immunity law, two referendum questions also ask Italians whether the ageing water supply network can be contracted out to private companies and where utility firms can retain profits from water bills.
Referendum supporters have stepped up a "get out and vote" campaign in recent weeks with a series of rallies as well as some more unusual initiatives.
Beach resorts in the region around the southern city of Naples are offering rental of two deck-chairs for the price of one for people who have voted.
Voters are also being offered discounts in bars and restaurants across Italy along with free massages, yoga classes and even concert tickets.
