The centre left is strongly leading in Italy's election, 5-6 percentage points ahead of the centre right of former premier Silvio Berlusconi, according to two telephone polls of voters.
A poll for Sky television published after voting ended at 1400 GMT (9 a.m ET), showed the anti-establishment protest movement of Beppe Grillo taking third place.
It showed the centre left ahead by 5.5 points in the lower house and by six points in the Senate although the result there will depend on key battleground regions. In the most important, Lombardy, Sky said the centre left was tied with Berlusconi.
Sky had the centre left of Pier Luigi Bersani on 34.5 percent, Berlusconi's centre right on 29 percent, Grillo on 19 percent and Monti slumping to 9.5 percent after a lackluster centrist campaign that deeply disappointed his backers among foreign governments and investors.
A phone poll for RAI state television showed a similar line-up with the centre left six points ahead of Berlusconi in the lower house.
The spread between Italy's benchmark 10-year bonds and the German equivalent narrowed to 260 basis points after the poll results in a sign of investor optimism that the centre left will be able to form a stable, pro-reform government.
The picture could change after computer projections of the result in both houses which are expected after 1500 GMT/ 10 a.m. ET.
Italy's electoral laws guarantee a strong majority in the lower house to the party or coalition that wins the biggest share of the national vote.
However the Senate, elected on a region-by-region basis, is more complicated and the result could turn on a handful of regions, including Lombardy in the rich industrial north and the southern island of Sicily.
Italy, the euro zone's third largest economy, is pivotal to stability in the region as a whole. The period of maximum peril for the currency was when Rome's borrowing costs were spiraling out of control at the end of 2011.
A bitter campaign, fought largely over economic issues, has been closely watched by financial markets, anxious about the risk of a return of the kind of debt crisis that took the whole euro zone close to disaster and brought technocrat Prime Minister Monti to office in 2011.
A surge in protest votes supporting the 5-Star Movement had raised deep uncertainty about the chances of a strong, stable government that could fend off the danger of a renewed euro zone crisis.
But Italian stocks and bonds rose before the end of the election as traders bet on a pro-reform government possibly backed by outgoing Prime Minister Mario Monti.
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