There were protests in other cities as well, with at least one protester in Milan reportedly heading to the hospital after a brawl with police.

Berlusconi has seen his support levels erode in recent months because of a series of influence peddling and sex scandals, a weak economy, several pending lawsuits, and the defection of Fini and several other key allies.

Earlier Tuesday, Berlusconi comfortably won the confidence vote in the Senate 162 votes to 135, with 18 Senators either absent or abstaining. But that vote was less of a surprise, because Berlusconi retained a majority there despite the recent problems.

With the victory, Berlusconi will hold onto power -- for at least a few months. Political pundits in Italy were already saying that if the prime minister managed to hold onto power by only a small margin his government would be too unstable to govern for long.

As things stand, a walkout by just a handful of parliamentarians would renew the political crisis and again bring the government to its knees.

But Berlusconi, who on Monday told parliament that changing governments during a political crisis was "irresponsible," vowed he would serve out the remaining two years of his mandate by reshuffling his cabinet to give more power to his supporters and negotiating a new legislative agenda to solidify his support.

But critics charge that allegations of vote buying would make it hard for Berlusconi to hold onto power for more than a few months.

Berlusconi's opponents were defiant.

"We have a prime minister who is derided and ridiculed abroad and who bought opposition deputies to ensure his majority," said Antonio Di Pietro, one of the opposition leaders.