Still, the center-left parties polled enough to slightly outnumber Berlusconi and his allies, something the opposition took as a victory.
"We can look to the future with the solid optimism of a force that has won the elections," Francesco Rutelli, a top politician in the center-left coalition, said Monday. "With these votes, the center-left would be in government."
However, in Spain and Greece, with recently elected governments, the ruling parties did well in the vote.
Spain's Socialist Party said its narrow victory showed that its election in March was not a fluke.
The Socialists had ousted the incumbent Popular Party amid anger over government support for the Iraq war and belief that that policy brought on terrorist attacks.
Daniszewski reported from London and Wilkinson from Rome.
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Continent's voters voice discontent
The European Union's parliamentary elections, which saw a turnout of just 45%, were marked by apathy and protest votes as citizens of many of the 25 EU nations punished their governments.