Italian Prime Minister Silvio Berlusconi's fate hung by a thread Friday and desertions from his crumbling centre-right coalition may have already robbed him of the parliamentary numbers he needs to survive. Berlusconi, caught in the crossfire from European powers and a party revolt at home, agreed at a G20 summit in France to IMF monitoring of economic reforms which he has long promised but failed to implement. But this may soon be irrelevant for the Italian leader, who will return to Rome later Friday to face what looks increasingly like a deadly rebellion by his own supporters. With financial markets in turmoil over the situation in Greece and Italy viewed as the next domino to fall in the euro zone crisis, calls are mounting for a new government to carry through reforms convincing enough to regain international confidence. Berlusconi has consistently rejected calls to resign and says the only alternative to him is an early election next spring, rather than the technocrat or national unity government urged by many politicians and commentators. Yields on 10-year Italian bonds reached 6.36 percent by early afternoon, creeping closer to 7 percent, a level which could trigger a so-called "buyers' strike" where investors take fright and refuse to buy the paper. Two deputies from Berlusconi's PDL party this week defected to the centrist UDC, taking his support in the 630-seat lower house of parliament to 314 compared with the 316 he needed to win a confidence vote last month. But at least seven other former loyalists have called for a new government and could vote against the 75-year-old media magnate. "The (ruling) majority seems to be dissolving like a snowman in spring," said respected commentator Stefano Folli in the financial daily Il Sole 24 Ore. Other commentators spoke of an "inexorable" revolt against Berlusconi. Even Defence Ministry undersecretary Guido Crosetto, a Berlusconi loyalist, said on television: "I don't know how many days or weeks the government has left. Certainly a majority relying on a few votes cannot continue for long." PATRONAGE Berlusconi, one of Italy's richest men, still has significant powers of patronage and he and his closest aides are expected to spend the weekend trying to win back support for a parliamentary showdown Tuesday. Some rebels have already threatened to vote against Berlusconi in the vote to sign off on the 2010 budget. Berlusconi faced concerted calls to resign when he lost a previous vote on this routine measure, which was almost unprecedented. Although it is not a confidence motion, he would come under huge pressure if he suffered a second defeat. "Unpopular prescriptions are necessary and this challenge cannot be faced with a 51 percent government," said UDC leader Pier Ferdinando Casini, in a reference to Berlusconi's weakness and a widespread feeling that the reforms can only be passed with a broad consensus. The premier has promised European leaders that he will call a formal confidence motion within 15 days to pass amendments to a budget bill incorporating new measures to stimulate growth and cut Italy's huge debt. That will be in the Senate where he has a more solid majority but it could still bring him down. Berlusconi, beset by a string of sex scandals and court cases, has consistently resisted pressure from groups ranging from a powerful business lobby to the Catholic Church to stand down.