ROME — Silvio Berlusconi is back in the running to become Italy’s prime minister following the fall Thursday of the center-left government headed by Romano Prodi, who defeated the Italian media mogul in the 2006 elections.

Prodi’s shaky 20-month-old coalition collapsed when it lost a crucial confidence vote in the Senate, forcing him to resign.

“Now we have to go to the polls,” a smiling Berlusconi said on Rete 4, one of three stations operated by his Mediaset broadcast group, which collectively commands a 40% national audience share.

“We will soon tell you our program for our first 100 days in government,” added Berlusconi.

His recently renamed Party of Freedoms is currently Italy’s strongest political force, with support of about 30%, according to several polls. Berlusconi, 71, got 24% of the vote when he lost to Prodi in 2006 after a full five-year mandate as prime minister.

Italian President Giorgio Napolitano can now either call early elections or try to form another government.

Berlusconi himself has said he would like to go to the polls in the spring.

The end of Prodi’s short-lived stint at the head of Italy’s 61st postwar government is good news for Mediaset.

A media law on the outgoing parliament’s agenda capping advertising revenues for broadcasters could have cost Mediaset up to $1 billion, Mediaset VP Piersilvio Berlusconi said last week.