By Gavin Jones
ROME (Reuters) - Prime Minister Matteo Renzi appealed on Monday to dissidents within his party to support a fiercely contested proposal for electoral reform, saying the dignity of the ruling Democratic Party (PD) is at stake.
The reform, which has been under discussion in the Italian parliament for more than a year, began a second reading in the lower house Chamber of Deputies on Monday, with up to 100 rebel PD lawmakers continuing to call for changes.
Renzi says the shake up is necessary to give Italy more stable and efficient government and is determined to have it approved by the end of May at the latest. It is contested by a sizeable minority of PD lawmakers as well as all the opposition parties on the right and left.
"If this electoral law doesn't get through then the idea of the PD as a motor of change for Italy will disappear," Renzi said in an open letter to the party, posted on its website.
"In the upcoming votes the electoral law is clearly at stake, but what is also and above all at stake is the dignity of our party," he wrote.
Renzi, who has often been criticized for concentrating too much on electoral and constitutional reforms rather than economic ones, has staked his reputation on the new voting rules. On Friday, he said in a television interview that the government would fall if they were not approved.
Renzi said he would decide on Tuesday whether to put the reform to a vote of confidence. That would amount to a "back me or sack me" strategy, because if he were to lose such a vote his government would be forced to resign.
The proposed electoral law, dubbed the "Italicum", would introduce a two-round voting system and a large winner's bonus of seats to the party that takes the most votes.
Opponents say this bonus is excessive and undemocratic, and they are also unhappy about provisions that would let party bosses handpick candidates, saying this will concentrate too much power with the leadership.
Center-right leader Silvio Berlusconi negotiated the reform with Renzi and voted in favor in earlier readings, but withdrew his backing earlier this year after Renzi refused to propose a commonly agreed candidate as head of state.
Renzi has a majority of around 70 seats in the Chamber of Deputies. This would be at risk if all the PD rebels were to vote against the bill.
If amendments are made to the bill it would have to return to the Senate for another reading. This would further increase the risks for Renzi because his Senate majority is much slimmer.
If the bill is approved unchanged in the Chamber of Deputies it will become law, but it will only take effect in July 2016.
(additional reporting by Roberto Landucci)