Growing concern over the rise of a new radical protest party that wants to see Italy exit the eurozone dominated the final day of campaigning Friday for general elections.
Political analysts say the Five Star Movement of comedian Beppe Grillo could win as much as 20 per cent of the vote and come in third at the polls.
Former foreign minister Franco Frattini went a step further in an interview with French newspaper Le Figaro, saying: "I am not ruling out that his movement will arrive second."
Polls open at 8 am (0700 GMT) on Sunday for voting over two days. Political parties were required by law to wrap up their campaigns Friday.
Grillo is to end his so-called "tsunami tour" in Rome, with a street event that was expected to draw tens of thousands of people. Although he has been fronting the movement's campaign, he is not standing for parliament.
The comedian is tapping into the widespread resentment against a ruling political class that is seen as corrupt and unable to lift Italy out of crisis.
He told US broadcaster CNBC, it was "only a matter of time."
"Either they give up now or they give up in six months, one year at most. No government can rule a country in ruins, and most certainly those who reduced it to ruins cannot be allowed to govern it," Grillo said. Italy's gross domestic product is set to shrink by 1 per cent this year and the unemployment rate is to rise to 11.6 per cent, the European Commission said Friday.
A strong poll showing for the Five Star Movement would be "a tragedy" marking "the failure of European ideals in Italy," Frattini told Le Figaro.
Such an outcome could complicate any bid to form a stable government, some political analysts have said.
Pier Luigi Bersani, leader of a centre-left coalition, is the frontrunner in the election. He is seen to risk falling short of a few seats in the Senate, where Grillo has said his deputies would remain in opposition.
The comedian's policies were dangerous, Bersani said ahead of his final rally in Rome.
"He worries me when he says we should leave the euro or that we should not pay our debts. If somebody like him wins, we would be in trouble within 48 hours," Bersani said.
Mario Monti, the outgoing premier and leader of the centrist coalition that is likely to become Bersani's coalition partner, struck a similar chord.
"Populists would like to take advantage of people's anger to smash everything. The battle in this elections is between populists and reformers," Monti told supporters in Florence.
Silvio Berlusconi, whose centre-right forces were trailing Bersani by less than 5 percentage points before a curfew on opinion polls was enforced on February 8, said a victory by the left would expose Italy to "bureaucratic, judicial and tax oppression."
The scandal-prone politician, who is on trial for paying for sex with a minor and is appealing a tax fraud conviction, has campaigned on an anti-austerity ticket and pledges to scrap an unpopular property tax, reimbursing Italians what they paid for it last year.
This week, he wrote to millions of voters explaining how they would be able to get their money in cash if they voted for him. Some people mistook it for an official letter from tax authorities and queued at post offices to claim their tax refunds, reports said.