Silvio Berlusconi has given a speech to supporters in Rome just hours ahead of a Senate vote on his political future.
Hundreds of fans have gathered outside his Rome palazzo, some carrying flags and wearing Berlusconi masks.
"In these past 20 years, if there is one thing I can't complain about, it's your closeness, your affection," he told the crowd.
He later declared today "a day of mourning for democracy".
A supporter wearing a mask outside Berlusconi's Rome palazzo
A banner hung from one of the windows of the palazzo reading "It's a coup".
The Italian Senate will vote later on whether to expel Berlusconi from Parliament over his tax fraud conviction.
Berlusconi is widely expected to lose his seat as both Prime Minister Enrico Letta's centre-left Democratic Party (PD) and former comedian Beppe Grillo's anti-establishment Five Star Movement have indicated they will vote against him.
A supporter waves a Forza Italy (Go Italy party) flag
In August, Berlusconi was convicted of manipulating tax bills for his television empire Mediaset, but the billionaire claims he didn't receive a fair trial and the judges were trying to "eliminate" him from public office.
The court heard how he was behind a scheme to purchase the rights to broadcast US movies on Mediaset television networks through a series of offshore companies, and had falsely declared the payments to avoid taxes.
The former prime minister was sentenced to four years in jail, which was reduced to one year and will likely be served as community service, and banned from holding public office for two years.
Supporters gather for a planned rally outside Berlusconi's Rome palazzo
Under a law passed last year, politicians convicted of serious criminal offences are ineligible for parliament, but his expulsion must first be voted on by the Senate.
Berlusconi sent a letter to opposition senators this week warning that removing him from Parliament would reflect badly on Italy's public image. He said the move would "shame you in front of your children, your electors and all Italians".
Losing his seat will deprive Berlusconi, who is fighting a conviction for paying for sex with a minor among other legal cases, of his parliamentary immunity from arrest.
Dancer Karima El Mahroug, known as Ruby the Heart Stealer
In June, the three-time prime minister was found guilty of paying for sex with underage prostitute, Karima El Mahroug, also known as Ruby the Heart Stealer.
During his trial, the court in Milan heard dozens of young women, including Miss El Mahroug, who was 17 at the time, were paid with cash and cars to attend Berlusconi's so-called "bunga bunga" parties and dance semi-naked for him.
Berlusconi's lawyers said it's "completely unrealistic" he will be arrested over the case.
Berlusconi is a 20-year veteran of Italian politics
The expulsion is expected to do little to affect Mr Letta's government which survived a confidence vote on the 2014 budget.
The vote was supported by a group of senators who broke away from Berlusconi's party.
Berlusconi pulled his party out of Mr Letta's ruling coalition earlier this year, accusing opponents of a "coup d'etat" to get rid of him.
However, even outside parliament, many believe the 20-year political veteran could still remain a nuisance to Mr Letta's government.