Nevertheless, Berlusconi made a last-ditch bid to save his seat this week, sending a letter to opposition senators warning them that kicking a three-time premier out of public office would tarnish Italy's image abroad and weigh on their consciences, "a responsibility that in the future will shame you in front of your children, your electors and all Italians."
Berlusconi remains head of his relaunched Forza Italia party, which on Tuesday officially withdrew its support of the government of Premier Enrico Letta and is now in the opposition.
Despite the switch, Letta's government comfortably survived a confidence vote early Wednesday and passed the annual budget. He survived because Berlusconi's one-time political heir, Angelino Alfano, split from his mentor earlier this month and formed his own new center-right party that remains loyal to Letta.
Analysts said they expected Letta's government — a hybrid of his Democratic Party and Alfano's New Center-Right — would continue in the short term.
The opposition, however, now includes two strong leaders: Berlusconi and Grillo, whose populist Five Star Movement encapsulates the discontent many Italians feel with the country's byzantine politics.
"Berlusconi by himself doesn't have the strength to bring down Letta's government, but he's going to make it more difficult for the Democratic Party to stay in the majority," said Giovanni Orsina, deputy director of the school of government at Rome's LUISS University. "I think Silvio Berlusconi can do some damage to this government."
James Walston, a professor of international relations at the American University of Rome, said the vote and rally essentially mark the start to a new electoral campaign in which Berlusconi won't be running for office but will be very much a protagonist as the head of a party.
"Berlusconi over the last few days has been conducting a very strident campaign," Walston said, referring to his letter to the opposition senators. "This is Berlusconi laying down part of his program for what he hopes is going to be elections very shortly."
Meanwhile, Berlusconi still faces other legal problems, including a seven-year prison term and lifetime ban from holding public office for his conviction of paying an underage prostitute for sex at his infamous "bunga bunga" parties and trying to cover it up. He has professed his innocence and plans to appeal.
