By James Mackenzie
ROME (Reuters) - Italy's center-left alliance showed new signs of division on Wednesday after the chief rival to Democratic Party leader Pier Luigi Bersani denounced the party hierarchy as efforts to form a government enter a critical phase.
The deadlock has left the euro zone's third-largest economy with only a caretaker government in charge as it slides further into a recession that many analysts expect will last until at least next year.
Matteo Renzi, the 38-year-old mayor of Florence who challenged Bersani unsuccessfully in a party primary last year, has voiced increasingly open dissent as the long stalemate since February's inconclusive election has dragged on.
He has so far not attacked Bersani by name but has called for an end to the impasse since the vote, saying the center-left must either drop objections to dealing with Silvio Berlusconi's center-right bloc or accept the need for new elections.
"Personally I'm one of those who hopes we vote as soon as possible because the elections did not produce a majority," he said. "Every day we wait is a day wasted for Italy."
In a sign of the mounting friction in the center-left, he accused unnamed Democratic Party officials of working to undermine him behind the scenes.
"I'm only sorry about the duplicity of people who talk in one way and act in another. I'd only say to these two-faced people: maybe I won't succeed in changing politics but politics won't change me," he wrote on his Facebook page.
Behind the backbiting is a potentially serious breach within the center-left, which has struggled to contain its divisions since Bersani failed to secure a viable majority in parliament despite a strong opinion poll lead before the vote.
More than 40 days after the election on February 25, the divided political parties are still no closer to reaching an agreement which would allow a new government to be formed.
Boosted by opinion polls which suggest the Democratic Party (PD) could win 32.5 percent of the vote with him at its head compared with 28.2 percent under Bersani, Renzi has made clear his ambition to lead the center-left if new elections are held.
For his part, the 61-year-old Bersani has said that fresh elections would be a disaster, although he has ruled out a so-called "grand coalition" with Berlusconi.
The immediate cause of Renzi's anger was his failure to be chosen as one of the regional representatives taking part in the election of Italy's next president to succeed Giorgio Napolitano, whose term expires on May 15.
The selection of the president is the next big test facing the rival parties, which vote in a joint sitting of the two houses of parliament, along with representatives from the regions.
After a close vote by the PD group in the local government of his home region of Tuscany, Renzi was not selected as one of the region's three electors, prompting him to blame unidentified "telephone calls from Rome".
Bersani denied any involvement in an interview on Rai 1 television on Wednesday.
"I made absolutely no such phone call," Bersani said, adding that the selection of electors was the least of the PD's problems at the moment as he reaffirmed his determination to form a government.
The breach between the two will weigh on efforts to hold the party together as the deadlock left by the election continues.
Bersani met Berlusconi on Tuesday to try to find some ground for agreement ahead of the vote for president. The two sides said the encounter went well but there was no sign of any agreement on forming a government.
(Additional reporting by Catherine Hornby, Editing by Mark Heinrich)