(see related stories) Rome, December 6 - Democratic Party leader Pier Luigi Bersani admitted Thursday that Premier Mario Monti's administration risked collapsing after Silvio Berlusconi's People of Freedom (PdL) party deserted a Senate confidence vote for a government economic-development bill. "We'll have to see if it is an abstention from one vote or a political abstention," said Bersani, who will be the centre-left's premier candidate at upcoming elections after winning a primary last weekend. "I'll get an outline of the situation with the whips and this evening I'll know whether there is a majority or not". There has been speculation the PdL, the biggest party in parliament, could withdraw its support from the government to provoke early elections in which Berlusconi would stand for a fourth term as Italian premier. The media magnate said he would retire from front-line politics after being forced to resign from the helm of government to make way for Monti's emergency administration last year, when Italy's debt crisis threatened to spiral out of control. But the 76-year-old has changed his mind several times in recent months over whether to return, with his centre-right PdL party struggling in the opinion polls and ravaged by internal divisions. Berlusconi said he was "besieged by requests from the party to announce as soon as possible my return to politics to guide the PdL" after a meeting with PdL top brass on Wednesday. Bersani said the actions of Berlusconi's party risked destabilising the country, which was expected to go to the polls in March. "The PdL has transferred the confusion inside itself to cause system confusion which is endangering the country's reliability," he said. The spread between 10-year Italian bonds and the German benchmark, an important barometer of market confidence in Italy's ability to weather the eurozone crisis, shot up after the PdL announced it was deserting the Senate vote. The spread edged up by one point to 311 after the opening of business on Thursday but then soared to 327 following the PdL's move.