ROME — Italian lawmakers voted on Tuesday to cut the number of seats in the national parliament, starting from the next general election.

According to the reform — which will still need to be approved in a nationwide referendum before it becomes official, as it requires amending Italy's constitution — the number of seats drops from 630 to 400 in the lower house and from 315 to 200 in the senate.

An overwhelming majority of 553 lawmakers voted in favor, while only 14 voted against. The governing coalition, which is comprised of the anti-establishment 5Star Movement and the center-left Democratic Party (PD), voted for changes alongside the far-right League, the far-right Brothers of Italy and Silvio Berlusconi's Forza Italia.

Cutting more than a third of seats was one of the 5Stars' flagship campaign pledges as part of their historic battle to cut the cost of politics and slash privileges for lawmakers. According to economists' calculations, the decrease would allow the state to save between €285 and €500 million per five-year parliamentary term — which critics have slammed as "petty" figures.

Tuesday's vote is the fourth on the 5Stars' proposed seat number reform and marks the first time the PD has voted in favor of the 5Stars' plan.

In 2016, the PD government proposed a different, more far-reaching reform to cut the number of lawmakers and change the country's parliamentary system, but the plan was rejected by voters in a referendum that led to Matteo Renzi's resignation as prime minister.

Renzi's new party, made up of lawmakers who split from the PD last month but who remain part of the governing coalition, also voted in favor of the proposal on Tuesday.

After the 5Stars' coalition with the far-right League collapsed this summer, 5Star leader Luigi Di Maio said it was absolutely vital the number of lawmakers was cut before Italians head back to the polls. (A new election was averted by the 5Stars agreeing to form a coalition with the PD.)

But the 5Stars' proposal (like Renzi's in 2016) has been strongly criticized by some law experts who argue it will decrease democratic representation.

Italy's current ratio is 1.6 lawmakers per 100,000 inhabitants. After the reform, it will become approximately 1 lawmaker per 100,000 — which critics say is too low and will end up concentrating too much power in the hands of party leaders.

To compare, Germany has a ratio of 0.9 lawmakers per 100,000 inhabitants, France's ratio is 1.4 lawmakers per 100,000 inhabitants and the U.K.'s ratio is about 2.1 lawmakers per 100,000 inhabitants.

The comparison is not straightforward, however: In the U.K., members of the House of Lords are not elected, unlike Italian senators. And while Germany's upper chamber, the Bundesrat, consists of only 69 members — representatives of federal states — the 16 states also have their own regional parliaments with a combined seat number of more than 1,800.