The result of Italy's general election hangs in the balance this evening with early results suggesting a very slender lead for Prime Minister Silvio Berlusconi.
Italian Premier Silvio Berlusconi casts his ballot in Milan yesterday
Mr Berlusconi's centre-right coalition may just win a shock majority in both houses of parliament.
A second pollster predicted that centre-left challenger Romano Prodi would just hold off Berlusconi, leaving the the result of the two-day vote on a knife-edge.
Exit polls at the end of the two-day ballot said Mr Prodi had won the election, taking between 50-54 per cent of the vote. But as the count proceeded, Nexus pollsters said the centre-right was advancing and could eventually end up the winner.
Centre-left leaders reacted with dismay and disbelief as the polls changed direction, revealing a country split in two after five years of Mr Berlusconi government.
Centre-right leaders were cautious, saying they would wait for official results due later this evening before commenting.
Nexus said that on the basis of its analysis of returns six hours after polls closed, the centre-right was on course to win 158 of the 315 Senate seats up for grabs.
In the lower house, Nexus predicted the centre-right would take 50.0 per cent of the vote against 49.5 percent for Prodi.
Under the terms of a highly controversial reform of the electoral system introduced by Mr Berlusconi last year, the winner in the 630-seat lower house is automatically assigned 340 seats to enable it to control the chamber.
The Nexus projection was at odds with the official count, which put Mr Prodi out front with 52.5 per cent of the vote after 40 per cent of returns for the lower house had been counted.
Piepoli pollsters for Sky Italia television said they would stick to their original forecast of a Prodi win.
Italy's two houses of parliament duplicate each other's functions and a government needs the support of both to take office and then to pass laws.
"Different majorities in the Senate and the Chamber of Deputies, as now looks possible, would be the worst possible scenario for markets," said Luigi Speranza, economist at bank BNP Paribas.
The interior ministry said turnout at the election was a high 83.6 per cent against 81.4 per cent in 2001. Berlusconi had argued that a turnout above 82 per cent would help his coalition.