Italy’s politics may soon be reshaped fundamentally if Silvio Berlusconi and Matteo Renzi, the leaders of the country’s two biggest parties, get their way.

The two have agreed to reform Italy’s electoral system, which left neither the left nor the right with a governing majority last year, resulting in months of bickering before a “grand coalition” was formed that has since been unable to pass major reforms.

The deal also aims to change the balance of power between the two legislative branches that has often led to weak majorities in the Senate.

Little enthusiasm

Few politicians welcomed the deal, which they believe could be unfair to small parties.

Many of Renzi’s own Democrats have been critical of their leader for reaching out to Berlusconi at all. The former premier was expelled from Senate in November after a conviction for tax fraud. Gianni Cuperlo, Renzi’s opponent in a leadership contest last year, resigned as party president in protest.

Proposed reforms

Under the new law, a party or coalition of parties that wins at least 35 percent of the votes would automatically get a majority of the seats in the lower chamber of parliament.

If neither party or alliance wins 35 percent support, a runoff would be held between the two largest parties.

Parties would also have to cross a 5- to 8-percent threshold to qualify for seats.

Combined with an overhaul of the upper chamber, which would lose its veto power and be reduced to regional deputies, the reforms would effectively give the largest party the power to govern unopposed.

Small parties wary

It would also prevent smaller parties from running outside coalitions.

The separatist Northern League immediately rejected the proposal for this reason, as did small centrist parties.

Deputy Prime Minister Angelino Alfano, who broke with Berlusconi to form his own party last year, cautioned that no deal is possible without him.

“We want coalitions and not just two parties, which goes counter to Italian history,” he said.

Five Stars

Beppe Grillo’s Five Star Movement is also critical, even if, under the proposed law, it could have won more seats.

In a runoff between the Democrats and the anti-establishment movement, it is not unthinkable Grillo would have prevailed.

The Five Star Movement polls at 21 percent support, close to Berlusconi’s new party, Forza Italia, but trailing Renzi’s Democrats, who are at 34 percent.

Renzi’s rise

If the bill becomes law, it would be one of the biggest political reforms in Italy’s republican history.

It would end the country’s perfect bicameralism as well as the proliferation of small parties that has often compromised government stability while only serving parochial interests.

Renzi has taken a risk by working with Berlusconi, who is widely despised on the left. He increasingly dictates government policy, overshadowing Letta.

The mayor, like Berlusconi, is in the unusual position of proposing comprehensive reforms from outside the government, even from outside parliament.

Letta’s administration is likely to last at least through the Italian presidency of the European Union in the second half of this year, meaning elections could be called, at their earliest, in 2015.

Renzi has until then to persuade disappointed Democratic Party voters to give him another chance while keep disgruntled leftists at bay — all without putting too much strain on the ruling coalition.