By Roberto Landucci
ROME (Reuters) - Italian Senators will vote on November 27 on whether to expel center-right leader Silvio Berlusconi from parliament over a conviction for tax fraud, officials said on Tuesday.
The vote has the potential to trigger a new crisis for Prime Minister Enrico Letta's fragile ruling coalition of left and right, given Berlusconi's repeated threats to pull his People of Freedom (PDL) group out of the government if Letta's center-left Democratic Party (PD) votes for his expulsion.
Luigi Zanda, the PD floor leader in the Senate, told reporters the date had been set for November 27 at a meeting of group leaders from all the main parties, but it had not been a unanimous decision and would have to be confirmed by a vote in the upper house.
Former Prime Minister Berlusconi's political future has been hanging over the government ever since August when Italy's top court confirmed his conviction over tax fraud at his Mediaset television empire and sentenced him to four years' prison, commuted to a year under house arrest or in community service.
A Senate committee decided last week the vote would not be held as a secret ballot, according to normal practice with votes on individuals but through an open tally, a decision which caused fury in the PDL.
Under an anti-corruption law passed last year, Berlusconi's conviction renders him ineligible to sit in parliament although his expulsion has to be confirmed in a vote in the Senate, where his supporters are in a minority.
Berlusconi has always protested his innocence, saying he is the victim of left-wing magistrates who want to bring him down for political reasons, and he has threatened repeatedly to bring the government down if he is expelled from parliament.
One attempt to do so failed last month when rebels from his own party refused to follow his instructions to vote against Letta in a no-confidence vote, forcing him into a humiliating climbdown and opening a split in the PDL.
However party secretary Angelino Alfano, leader of the rebel group which defied Berlusconi, said on Tuesday the 77-year-old former prime minister had promised his backing to the government.
"He confirmed his confidence in the government and I think a stable government, combined with our existing progam is the key to preserving unity in our party," he told reporters.
(Reporting by Roberto Landucci; Editing by Angus MacSwan)