Rome, January 20 - New leader Matteo Renzi presented his proposals for a new election law to a meeting of his Democratic Party (PD) in Rome on Monday after reaching a controversial deal with ex-premier Silvio Berlusconi on Saturday.

Renzi, the ambitious 39-year-old mayor of Florence who won a primary to lead Italy's biggest party last month, said that his proposals were "concrete" and could be approved by the end of May. The deal has come under fire from some parts of the PD, who say it serves as a political rehabilitation for Forza Italia chief Berlusconi, who was ejected from parliament after a definitive tax-fraud conviction last year. Renzi has said it is only logical to try to find an agreement on the election system with the second-biggest party and argued the PD and Italy's political class as a whole had to move quickly to regain credibility.

And despite the internal dissent, his proposals were approved by a PD meeting with 111 votes in favour, 34 absentions and none against. Italy needs a new election system to replace the old one that was recently declared invalid by the Constitutional Court.

The political parties failed for years to find an agreement on a new system, even though the old one, which was nicknamed the 'pigsty' and was blamed for contributing to the inconclusive outcome to last year's general election, was widely recognised to be dysfunctional.

That election result led to two months of deadlock and then the swearing-in of the weak left-right coalition government of Renzi's PD colleague, Premier Enrico Letta. "We are trying to regain lost dignity," Renzi said. "The time has come to show that politics is not just talk, talk, talk. We have to decide if we're going to be political or bar sport". Renzi warned his own party, Forza Italia and the junior partners in Letta's governing coalition that his proposals were not amendable. "It's a complicated castle that only stands up if all the pieces are together," Renzi said. "If someone intervened in parliament to change something, it would wreck everything".

Renzi said his proposed system, based on proportional representation, would feature a significant bonus for the coalition that comes first to ensure it can govern. A coalition that comes first and obtains at least 35% of the votes would get a bonus that would grant it between 53% and 55% of the seats in parliament, with the maximum bonus being 18%. He said that if no coalition obtains 35% or more of the vote, his proposal is for a second round of voting between the top two alliances.

Voters would not have the opportunity to express preferences for the candidates who they want to represent them on a party list. A big problem with Italy's former election law was that the system of long 'blocked lists' of candidates gave voters little power in selecting representatives. This, and the former win-bonus system, were among the reasons that the old law was ruled invalid by the Constitutional Court last month.

Renzi reportedly wants to get around the detachment this creates between elector and elected with smaller constituencies and lists of just four or five candidates so voters can have a better idea of who the potential MPs are in their area. He added that his proposal is for a threshold of 8% of the vote for a party to have seats in parliament to prevent the system being too fragmented. The threshold would be lower, 5%, for parties in a coalition. The proposals, and the way they were presented, were criticised at Monday's meeting. "If you say that (the package is untouchable), then there's no point in calling a party meeting again in two weeks," said Gianni Cuperlo, who unsuccessfully ran against Renzi in December's primary. "This election reform is not convincing because it does not guarantee adequate representation, nor the right of people to choose their elected representatives, nor reasonable governability," he had said before the meeting. "There are doubts about whether its Constitutional". The small parties in Letta's government alliance, who are threatened by the the thresholds on entry to parliament, have not ruled out the proposals.

Deputy Premier and Interior Minister Angelino Alfano, the leader of the New Centre Right, said they would be acceptable if three out of four of his demands were accepted, above all over the question of voter preferences.

The Civic Choice party of former premier Mario Monti said it was waiting for further details.

But the anti-establishment 5-Star Movement (M5s), which won about a quarter of the vote at last year's election, blasted the pact and said it will not sign up.

Renzi denied wanting to pass a new election law quickly so that he can scupper Letta's executive and provoke a fresh vote, in the hope of winning and taking his party colleague's place at the helm of government. The PD chief, who has repeatedly criticised the government since winning the party primary, said such speculation was "ungenerous".