ROME (Reuters) - A senior official of Italy's centre-left Democratic Party (PD) resigned on Tuesday over plans to reform the electoral system, underlining the tensions facing new leader Matteo Renzi as he tightens his grip on the party hierarchy.
Gianni Cuperlo, a former communist and an adversary of Renzi in the leadership primary in December, quit after clashing with the new PD secretary during a party meeting to discuss proposals to streamline Italy's tangled electoral rules.
Renzi, the 39-year-old mayor of Florence, heads the biggest party in Prime Minister Enrico Letta's left-right coalition but is not in government himself. His impatience with the party old guard has alienated sections of the PD's left wing.
Cuperlo stepped down as PD chairman, a largely symbolic office, declaring on his Facebook page that he would continue to fight for the ideals of a reformed left "without which this party would simply cease to exist".
His resignation follows that of former Deputy Economy Minister Stefano Fassina, a prominent member of the PD left wing who quit the government earlier this month in a dispute over Renzi's calls for Rome to step up the pace of reform.
Wider signs of party opposition have been limited and Renzi's electoral proposals, agreed in advance with centre-right leader Silvio Berlusconi, easily won 111 votes in favour and only 34 abstentions at a PD leadership meeting on Monday.
Cuperlo criticised elements of the proposals, which are intended to favour strong coalitions able to survive a full term in government, and lamented Renzi's refusal to allow extended discussion of or change to the package.
The system would include minimum thresholds for entry to parliament that would threaten the existence of small parties. It would also guarantee a strong majority to the winner, with a run-off round if needed to decide the result.
Discussion will begin in February on a separate but related series of reforms aimed at further reducing the risk of deadlock by concentrating power in a single chamber and converting the Senate into an unelected regional assembly.
(Reporting By James Mackenzie; Editing by Tom Heneghan)