Italian prosecutors have requested that former Prime Minister Silvio Berlusconi face trial for allegedly bribing a senator to switch parties.Mr Berlusconi is accused of paying a left-wing senator 3m euros ($3.9m) to defect to his right-wing People of Freedom party (PDL) in 2006.
Mr Berlusconi says he is a victim of a campaign by a left-wing judiciary.
On Saturday, he will lead a rally in the city of Brescia against a fraud conviction upheld on Wednesday.
In that case, Mr Berlusconi was convicted of artificially inflating prices of film distribution rights bought by his company, Mediaset, to avoid taxes.
The 76-year-old faces a four-year prison sentence and five-year ban from public office for that conviction, and is expected to appeal against the decision to Italy's highest court, the Court of Cassation.
Silvio Berlusconi's trials
- Accused of paying for sex with an underage prostitute: Verdict due
- Convicted and sentenced to a year in jail for arranging leak of police wiretap. Remains free while appeals process under way.
- Accused of tax fraud over deals his firm Mediaset made to purchase TV rights to US films: Convicted in October 2012; Sentence upheld by appeals court in May
- Two other corruption cases involving tax evasion and bribery of a British lawyer: Expired under statute of limitations
The corruption charges filed on Thursday relate to a payment allegedly made to Sergio De Gregorio, a senator from Naples.His defection weakened the government of Romano Prodi, which collapsed in 2008, and triggered elections that returned Mr Berlusconi to power.
A judge will now decide whether there is sufficient evidence to put Mr Berlusconi on trial.
Mr De Gregorio has said he took the payments from Mr Berlusconi, and has also been charged.
Prosecutors had an earlier request for a fast-track trial turned down.
Mr Berlusconi is also on trial in Milan on charges of paying for sex with an underage prostitute and abuse of power.
His People of Freedom Party recently joined a coalition government led by centre-left Prime Minister Enrico Letta.