Italy faces a period of uncertainty and political horse trading Tuesday after parliamentary elections left no party in a clear position to form a government.

The center-left coalition headed by Pier Luigi Bersani won by a narrow margin in Italy's lower house of parliament, according to final figures released by the Interior Ministry.

But Bersani's coalition, with 29.54% of the vote, finished less than half a percentage point ahead of the anti-austerity center-right coalition headed by controversial three-time Prime Minister Silvio Berlusconi, which garnered 29.18%.

It was a similar story in Italy's upper house, where the lack of a clear majority means that no one has a firm enough mandate to govern the country.

Final results showed the center-left winning the Senate with 31.63% of the vote, compared with the center-right's 30.72% -- an outcome that points to stalemate because of the way Senate seats are distributed.

"This is a case of gridlock," said James Walston of the American University of Rome. "Nothing could be worse for Europe."

International concern is high that Italy -- the third-largest economy in the eurozone and the eighth-biggest in the world -- could face fresh elections if no coalition government can be formed.

In any case, a weak government would probably struggle to push through the tough reforms many observers feel are needed to get the economy back on track.

Symbolizing Italians' own unhappiness with austerity and their political leaders, a quarter of the vote in the lower house went to the anti-establishment Five Star protest movement led by comedian Beppe Grillo, who has said he won't join forces with any established political parties.

A bloc led by Mario Monti, the former head of a technocrat government that steered Italy through the worst of the eurozone crisis last year, trailed badly in fourth place.

Markets reacted negatively to the uncertainty Tuesday, with fears about the eurozone crisis coming once more to the fore after months during which confidence had grown.

Even if Bersani can form a workable coalition, governing will be very difficult, and investors are concerned that a stalemate in the Senate could undermine the progress Italy has made in overhauling its troubled economy.

European markets, including Milan, were sharply lower in morning trading, while Asian markets also retreated.

U.S. stocks fell Monday amid the concerns about Italy, with the Dow and S&P 500 suffering their biggest one-day declines of the year. U.S. stock futures were indicating a rebound for stocks at the open on Tuesday.

Voter turnout was lower than anticipated Sunday, the first day of balloting, down from 62.55% in 2008 to 55.17% this year, Italy's ANSA news agency reported.

Weather, in part, appeared to cause the lower voter turnout, the news agency said. It was snowing in portions of northern Italy and raining in the southern part of the country.

Alliance-building

Italy's political system encourages the forming of alliances.

But if neither Bersani nor Berlusconi can build a strong enough coalition to govern, Italy could face another round of elections.

The center-left alliance dominated by Bersani's Democratic Party also includes the more left-wing Left Ecology Freedom party.

It was widely assumed ahead of the vote that the center-left would join forces with Monti's bloc, but its disappointing showing means that even together, they cannot command a majority in the upper house.

Bersani held a clear lead in polling in the weeks ahead of the vote but saw it slip away in the final days of the campaign.

Walston, the analyst, said ahead of the vote that the left had suffered from a lack of leadership, which prevented it from putting forward a clear picture. Bersani, 61, comes across as "bluff and homespun, and that's part of his appeal -- or not, depending on your point of view," said Walston.

The center-right alliance led by Berlusconi's People of Freedom Party, or PdL, in coalition with the right-wing, anti-immigration Northern League, made up significant ground in the final days of campaigning.

Berlusconi gave conflicting signals as to whether he was running for the premiership, indicating that he would seek the job if his coalition won, but contradicting that on other occasions.