Silvio Berlusconi
Former Prime Minister Silvio Berlusconi smiles as he casts his vote at the polling station in Milan (Reuters)

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Former prime minister Silvio Berlusconi has made an impressive comeback in Italy's national elections, leading the country into a political gridlock. Elections depict a scattered Italy.

The Left-wing coalition led by Pier Luigi Bersani's Democratic Party (PD) won 31.63 percent of preferences at the Senate, holding a narrow margin on Berlusconi's centre-right block (30.71 percent).

However Berlusconi' People of Freedom party (PDL) won in all the battleground regions (Lombardy, Veneto, Sicily, Campania and Puglia) preventing Bersani to gain a majority of seats in the House, even striking an alliance with PM Mario Monti. Bersani holds 97 of the total 315 seats, Berlusconi 110 and Monti 18.

"It is a very delicate situation. We will manage the result in Italy's best interest," Bersani said.

Thanks to a bonus granted under Italy's electoral law known as 'pigsty', with 29.55 percent of votes, Bersani holds a majority of seats at the Lower Chamber.

Former comedian Beppe Grillo's Five Star Movement showed a stunningly strong result in both houses.

Grillo's protest movement has become the major single party at the Lower chamber (25.55 percent) and the second at the Senate (23.79 percent), an almost unprecedented result for a political formation in its first national ballots.

"The first thing is the big surprising increase scored by the 5 Star Movement, and the other is the disappointing result" for Monti's coalition, said Massimo Franco, a columnist with Corriere della Sera.

Monti said to be "very pleased" by the result (Senate 9.13, Lower Chamber 10.56) obtained by his centrist coalition, which, however, hasn't gained enough seats to play a substantial role in the formation of a new government.

Thanks to a strong electoral campaign, Berlusconi has managed to rise from the 7 percent in the polls in November to a stunning 29.18 percent at the Lower Chamber.

"We have always been confident in this success," said PDL secretary Angelino Alfano. "We owe it to Berlusconi's grit and determination. He is a great leader.

"Those who thought Berlusconi was at the end of his days in politics and the centre-right had passed away have had to change their opinion."

Battling against the Italian establishment and corrupt political system, Grillo has tapped in to the public's anger at the old ruling class and technocrat Monti's harsh austerity measures as the country continues to lurch through the economic crisis.

Grillo has pledged not to join a governing alliance with any other party, a decision that will make it almost impossible for any other party to form a stable government.

"We've managed to become the largest Italian party in only three years, and without receiving public funds," said Grillo.  "Their [old parties] time is over."

The prospect of political paralysis raised the possibility of new elections in the coming months.

"It is a serious problem for Italy," PD member Stefano Fassina told La 7 television. "[If results are confirmed] we should find a way to reform the electoral law and call for new elections as soon as possible."