The weak performance of outgoing premier Mario Monti is key to a deeply uncertain and potentially unstable result.
Political leaders held their final rallies before a campaigning ban ahead of voting tomorrow and Monday.
"This vote is not at all certain," said one pollster, who asked not to be named because of a two-week ban on opinion surveys. "One percentage point either way could lead to chaos or a clear winner."
Analysts are divided over whether centre-left leader Pier Luigi Bersani will be able to form a stable majority capable of pursuing the economic reforms Italy needs to exit recession.
Mr Bersani is thought to be just a few points ahead of centre-right leader Silvio Berlusconi but is still seen as having a good chance of the winner's bonus that will give him comfortable control of the lower house.
However, the election will revolve around the much more complex Senate race, where winners' bonuses are awarded on a regional basis. The centre-left and centre-right are close to a draw in several regions.
Mr Monti is though to be fading, but analysts disagree about the implications.
Electoral expert Roberto D'Alimonte expressed concern that he may fall below the 8% threshold to win Senate seats in some regions, and said this could be disastrous for Italy.
"The future of Italy and the eurozone depend on this variable," he said.
The biggest danger is that the election produces a weak government incapable of decisive action, spooking investors and igniting a new debt crisis.