Florence mayor to take on Italian centre-left leader FLORENCE mayor Matteo Renzi is to challenge Pier Luigi Bersani for the leadership of Italy's centre-left, increasing the pressure on his rival by saying that he must either agree to form a coalition with former premier Silvio Berlusconi or demand a new election. Mr Bersani won a majority in Italy's lower house, but not the senate in February's elections, leaving the centre-left unable to govern alone. Last week, he failed to forge a viable majority in parliament when his overtures to the anti-establishment 5-Star Movement were rebuffed. Mr Renzi, 38, who lost to Mr Bersani last December in a vote to be the centre-left's leading candidate, gave interviews to several Italian newspapers yesterday saying he was ready to stand in a new primary election for the post. Mr Renzi had previously hesitated over challenging Mr Bersani, a former communist politician who blew a 10-point opinion poll lead to leave Italy in political deadlock. But in recent days he has become critical of Mr Bersani's line that a "grand coalition" with scandal-plagued centre-right leader Berlusconi is unthinkable. Another option could be a technocrat government sponsored by president Giorgio Napolitano, but this is opposed by both centre-left and centre-right. "We cannot stop here, waiting for Bersani to get support," Renzi told the daily La Repubblica. We must do something: a government formed by the president, a grand coalition, or we must return to vote. The Florence mayor, who had been widely expected to make his move after Mr Bersani failed to secure a working majority, rejected suggestions that party primaries could not be organised by June. Berlusconi's centre-right People of Freedom party (PDL) has repeatedly called for Mr Bersani to join it in a coalition or go back to the ballot box in June, although analysts say the chance is diminishing that an election can be held by then. A new election held under the current law would run a high risk of producing another deadlock, but there is thought to be no prospect of changing it before June. The law gives a big bonus in the lower chamber to the winning party, meaning that the centre-left can control the chamber despite its wafer-thin winning margin. However, the law also requires a new government to win a confidence vote in the senate, where seats are allocated regionally. A new vote would very likely produce another winner in the lower house who lacks a majority in the senate. Mr Bersani says a snap election would be a disaster when Italy needs a solid government to tackle a deep recession. Meanwhile, support for Berlusconi has been growing steadily in recent surveys, which show the centre-right overtaking the centre left. Mr Renzi, whose market-friendly views are seen as appealing to centre-right voters, said he could pose the most credible challenge to Berlusconi, who is awaiting verdicts in two trials, one on charges that he paid for sex with a minor. Berlusconi wants a vote in June precisely in order not to give me space. We can challenge him. If I run, he will be in trouble," Mr Renzi told La Repubblica.