By Paolo Biondi
VERONA, Italy (Reuters) - The young mayor of Florence launched a bid on Thursday to be Italy's next prime minister, a challenge to the old generation struggling with political chaos less than eight months ahead of an election.
Matteo Renzi, 37, seen as an arrogant upstart by the ageing political establishment, announced he would stand in primary elections to choose the prime ministerial candidate for the centre left, which is well ahead in the polls.
Renzi says he wants to "trash" the old political class and that Italy must turn to a new generation after years of misgovernment.
Renzi, who launched his candidacy at a rally in the northern city of Verona, aims to ride the same wave of disgust with traditional politicians that has helped comedian Beppe Grillo establish his populist Five Star Movement as a political force.
Pier Luigi Bersani, veteran head of Renzi's Democratic Party (PD), looks certain to win the primaries, expected in November, even if a recent opinion poll showed 37 percent of the general public would prefer Renzi as centre-left premier against 27 percent for Bersani, who is 60 years old.
Renzi's candidacy underlines the forces pushing traditional parties towards disintegration as an election approaches to choose a successor to Mario Monti's unelected technocrat government that is trying to steer Italy through the euro zone debt crisis.
European leaders and investors are worried by the uncertainty and fear a new government could renege on Monti's austerity policies that have done much to restore Italy's international reputation since the fall of scandal-plagued billionaire Silvio Berlusconi last November.
The head of the employer's lobby Confindustria, Giorgio Squinzi, said he hoped the poll - which must be held by April - would not add to Italy's problems. "Next year's elections are a question mark," he said.
LACK OF DETAIL
Renzi, a former marketing executive, is a slick, Internet-savvy communicator, but critics say he is all style and no substance and lacks detailed policies.
"The point is that we are all waiting for Matteo to say something. His political proposal is very hazy," said Pippo Civati, a PD regional councilor for Lombardy.
He is mockingly portrayed as a teenager by comedians while senior politicians say he would embarrass Italy on the international stage. "Renzi is unfit, unqualified to govern," said former centre-left premier Massimo D'Alema.
The political uncertainty is so great that Italy still does not know which electoral law will be used in the election.
Italy's politicians - on average some of the oldest in Europe - have been arguing for months about how to replace a voting law so bad it is called "the pigsty".
The centre left is holding its primaries on the basis of an electoral system that allows parties to form coalitions and declare a prime ministerial candidate before the vote. But that could change under a new law, making the primaries irrelevant.
Adding to the uncertainty, politicians are struggling to present themselves in a way that will attract skeptical voters, with some estimates saying 40 percent or more are undecided.
Some analysts believe the main parties, led by the PD and Berlusconi's People of Freedom (PDL), which have supported Monti's reforms in a broad but uncomfortable parliamentary alliance, will disintegrate before the vote.
The PD, already riven by internal divisions between former communist leftists and ex members of the Christian Democrat party, is trying to juggle a new alliance with a small leftwing party and attempts to form a block with the centrist UDC.
The UDC is bidding to attract leading figures, including ministers from Monti's government, into a group that would campaign on the promise to reappoint Monti or a respected technocrat like him so that painful reforms will continue.
On the centre right, Berlusconi's party is in disarray because of continuing uncertainty about whether he will stand as their candidate. The Corriere della Sera daily said the once dominant party had virtually disappeared in recent weeks.
Berlusconi, 75, himself appears to be waiting for opinion polls to tell him whether he would be humiliated in an election or could take enough votes to remain a force in parliament - and protect his business interests.
Renzi, on the right wing of the PD, said he would appeal to disgruntled members of Berlusconi's party to join him.
(Additional reporting by Massimiliano Di Giorgio; Writing by Barry Moody; Editing by Robin Pomeroy)