By Roberto Landucci
ROME (Reuters) - Italy's parliament on Monday gave final approval to a new electoral law championed by Prime Minister Matteo Renzi despite furious objections from the opposition and some members of the ruling Democratic Party.
The electoral overhaul, which becomes law after more than a year of discussion in both chambers of parliament, is a central part of Renzi's political and economic reform agenda.
The legislation, which only takes effect in July 2016, is based on proportional representation but guarantees a big majority to the winning party and gives party bosses wide powers to handpick preferred candidates.
Renzi says it will provide political stability to Italy, which has already seen four different governments since the start of the decade, and end the backroom horsetrading between parties often needed to form ruling coalitions.
"There will be a system in which our country will finally be a point of reference for political stability which is a precondition for economic and cultural development," Renzi said earlier on Monday.
Opponents complain that the new law concentrates too much power in the hands of the winning party and does not allow voters to directly choose their representatives.
Opposition parties have appealed to President Sergio Mattarella not to sign off on the bill in order to prevent it becoming law. They have also threatened to organize a popular referendum to try to have it repealed.
"We say no, because this law has been conceived to create a one-party state," said Renato Brunetta, floor leader of former Prime Minister Silvio Berlusconi's Forza Italia party. Forza Italia previously supported the bill, but changed its mind following a dispute over the election of Mattarella in January.
The 630-seat Chamber of Deputies approved the bill in a secret ballot by 334 votes to 61. With most opposition lawmakers refusing to take part, the result indicated that 40-50 dissidents in Renzi's Democratic Party (PD) voted against him.
Analysts said the chief beneficiary of the reform was likely to be the 40-year-old Renzi himself, who faces a weak and divided opposition and holds a clear lead in opinion polls.
Renzi brushed aside resistance from PD rebels last week by imposing confidence votes to prevent further amendments being added, which would have prolonged its parliamentary passage.
Together with a separate reform of the Senate that will see the upper house reduced to a non-elected chamber with limited powers, the overhaul is intended to ensure stable governments able to last a full five-year term.
Renzi said Italy, one of the world's slowest growing economies, had had 63 governments since World War Two but that none had been strong or durable enough to push through core reforms, despite wide recognition that change was needed.
(Additional reporting by James Mackenzie, writing by Gavin Jones and James Mackenzie; Editing by Janet Lawrence and Crispian Balmer)