MSNBC reports that Italian PM Romano Prodi wants to change the country's electoral law... again. His tenuous coalition government was dealt a blow when the hard left threatened to bolt over Iraq policy.

Mr Prodi wants to rid Italy of the system of proportional representation that was forced through parliament just before last April's general election by his predecessor, Silvio Berlusconi.

Although Mr Prodi won the election, the result was the closest in modern Italian history. The voting system in use denied Mr Prodi's nine-party coalition a guaranteed majority in the Senate, the upper house.

That boosted the bargaining power of small parties in his coalition, allowing them to hold the government to ransom. Mutual mistrust has taken root in the cabinet, obstructing the execution of economic and foreign policy.

Name-dropping "Italy" is a common way to convict proportional voting of any variant.

Matt Shugart at Fruits and Votes argues that Italy's system is not a form of PR. This is because the pre-election coalition winning a plurality of nationwide votes is guaranteed 55% of total seats - the idea being to foster party aggregation in a country with historically weak governing coalitions. There is some level of PR within each coalition, however.

Whether or not Italy's electoral system can be called proportional voting, it is unlikely, at least in the short to medium term, that switching to winner-take-all (as was done in 1993 for the same reasons) will knock deal-breaker parties into line. Even with single-member plurality districts, which electoral engineers expect to generate two-party systems, Italy's hard left performed well enough to tank Prodi's government in 1998.

The cause of Italy's instability is not proportional voting. It's regionalism. Regardless of the electoral system in place, that regionalism is likely to persist for a long time.