Italian lawmakers have approved a reform of the voting system that could disadvantage the populist Five Star Movement in the next election.

The reform allocates a third of the seats in parliament on a first-past-the-post basis, which should help the mainstream left- and right-wing parties.

It also removes a premium for the largest party, which had been ruled unconstitutional.

Combined, the changes could make it harder for the Five Stars to come to power, despite them polling neck and neck with the ruling center-left Democrats.

Tinkering

Italy has been tinkering with its electoral system for decades. Politico has a good overview.

The conflict has been between “majoritarians” and “proportionalists”. The former favor an American- or French-style system in which the biggest party automatically wins a majority. The latter argue for a system more like Germany’s, where coalitions are necessary.

The proportionalists had their way from 1946 to 1993, when Italy went through 52 governments in 47 years.

Berlusconi

The majoritarians have been on the ascendancy since Silvio Berlusconi entered Italian politics in the 1990s. He was able to govern despite only once winning over 50 percent support.

Berlusconi’s electoral law — which give 55 percent of the seats in the lower house to the top vote-getter — was overturned by the Constitutional Court in 2013. His conservatives promptly lost their majority to the Democrats in parliamentary elections that year.

Renzi

Left-wing leader Matteo Renzi attempted a similar reform: he would have given a majority to the party that won 40 percent support or more. Not coincidentally, his Democrats won 41 percent support in European elections in 2014.

But Renzi’s proposal was blocked by the Constitutional Court as well.

His simultaneous reform of the Senate — reducing the upper body to an almost powerless chamber of regional deputies — was blocked by voters in a referendum.