By Barry Moody and Steve Scherer
ROME (Reuters) - An opinion poll on Monday showed Silvio Berlusconi's party falling behind its center-left rivals and could undermine the media tycoon's temptation to bring down Italy's shaky coalition government over his tax fraud conviction.
Allies of Berlusconi, 76, have been threatening for weeks to bring down the left-right coalition of premier Enrico Letta if a Senate committee meeting this week votes to bar him from parliament.
However, the media magnate's mood is volatile and he has changed his mind from one day to the next as he listens alternately to hawks and doves in his own party as well as members of his family and officials of his business empire worried about the economic fallout from renewed instability.
In recent days, political sources have suggested the center-right leader is backing away from an immediate government crisis and elections for fear this could misfire.
A poll in La Repubblica newspaper by the Demos organization suggested this fear could be well-founded, showing Italians split three ways as they were in an inconclusive election last February which led to a damaging two-month impasse before President Giorgio Napolitano forced the parties into a cross-party coalition of the old rivals.
The poll showed the center-left PD on 28.5 percent, just ahead of Berlusconi's People of Freedom (PDL) on 26.2 percent. This is a contrast to polls before Berlusconi started his campaign against the conviction, which had the PDL well ahead.
It also showed the populist 5-Star Movement of comedian Beppe Grillo on almost 21 percent, below his 25 percent in the February election - which shook Italy's establishment - but enough to create another potential impasse.
Berlusconi's unpredictability has led to normally well-informed Italian newspapers printing conflicting headlines each day for weeks.
"I receive calls from investors, and they want definite answers about what will happen to the government if they are going to invest billions on Italian bonds," said Roberto D'Alimonte, one of Italy's top political analysts.
"I can't tell them because you have to be in Berlusconi's mind to know, and I don't think Berlusconi knows himself what he's going to do."
One journalist who has followed Berlusconi for 15 years told Reuters: "He is capable of changing his mind three times during a 40 minute conversation. His friends joke about it."
Commentators and analysts have repeatedly argued that if Berlusconi forces an election, not only could he suffer the anger of voters at political games in the midst of Italy's worst postwar recession, but end up in exactly the same kind of coalition as now because of another inconclusive result.
Worse, he could push the PD into a highly hostile coalition with Grillo's party. President Napolitano strongly opposes a new election given the economic crisis and is thought likely in such circumstances to ask Letta to try to form a new government.
Markets seem to be listening to these arguments, remaining remarkably sanguine despite the turmoil in Berlusconi's mind and Italian politics.
Italian bond yields have risen, but not markedly more than their peers. And the stock market is up nearly seven percent in the last two weeks, in line with the broader European index.
"I have argued all along that the Italian government is most likely to survive the present tensions over the political future of Berlusconi, but the very fact that this issue is on the table causes amazement and confusion among international investors," said Erik Nielsen, global chief economist at Italian bank Unicredit.
Italy's supreme court last month confirmed a four-year jail sentence on Berlusconi, commuted to one year, for massive fraud at his Mediaset television empire. He is expected to serve the sentence under house arrest or do community service, severely impairing his ability to campaign in an election.
Without all of his formidable campaigning power, the PDL would be expected to lose votes in an election.
The Demos poll showed that almost 50 percent of those surveyed had a positive view of the Letta government, which has struggled to pass vital economic reforms because of constant squabbling between the coalition members - exacerbated by the row over Berlusconi's conviction.
This suggests they would look dimly on anybody forcing a crisis. The public mood was summed up in a recent Twitter post:
"Hello police? We're being held hostage by a convicted criminal."
"Stay calm. How many of you are there?"
(Editing by Mike Peacock)