Italy’s parliament has approved fiercely contested changes to the country’s electoral system championed by Prime Minister Giorgia Meloni ahead of elections due next year.

Lawmakers voted 227 to 164 in favour of moving to a fully proportional system, which Meloni has argued will boost the chance of clear winners and more stable government.

Opposition parties say her right-wing coalition has designed the proposals to improve its chance of retaining power and, in a heated debate on Thursday, accused it of flouting democracy.

Meloni had warned she could resign and trigger an early election if the plans were rejected, with the secret ballot seen as a test of her authority.

Meloni’s coalition has overseen a rare period of political stability for Italy since her election in 2022, and last month her government became the country’s longest-running since World War Two.

The voting reform will see the country move away from its current hybrid voting system, in which about a third of members are chosen through a first-past-the-post vote and the rest through proportional representation.

Parties proposing to form a coalition will be required to put forward their joint candidate for prime minister, and their political programme, before any general election.

A party or coalition which emerges with the largest share of the votes – provided this exceeds 42% – will be awarded 105 additional seats in parliament (70 in the lower house and 35 in the senate), which could turn a narrow victory into a more comfortable majority.

In a debate ahead of the vote, centre-left members accused the government of forcing through the new voting rules.

“Go ahead and change the electoral law, we will win in any case under any voting system,” said Democratic Party (PD) leader Elly Schlein.