Italy's highly fragmented party system made it hard to identify an overall trend, but the results were generally seen as a defeat for Italian Prime Minister Silvio Berlusconi and a victory for the centre-left opposition coalition identified with Romano Prodi, who was President of the European Commission until 2004, and was widely expected to re-enter Italian politics at the next election.
While the Olive Tree's performance was not as phenomenal as it had hoped, the test indicated a somewhat reduced support for the centre-right coalition. However, in European elections, Italians tend to vote in a more candidate-oriented way, giving their vote more easily to a candidate outside their usual party; this generally reduces the significance of these elections.
The pure party-list proportional representation was the traditional electoral system of the Italian Republic since its foundation in 1946, so it had been adopted to elect the Italian representatives to the European Parliament too. Two levels were used: a national level to divide seats between parties, and a constituency level to distribute them between candidates. Italian regions were united in 5 constituencies, each electing a group of deputies. At national level, seats were divided between party lists using the largest remainder method with Hare quota. All seats gained by each party were automatically distributed to their local open lists and their most voted candidates.
Seats are allocated to party lists on a national basis using an electoral quota, with the residue given to the lists with the largest excess over whole quotas. An electoral quota is then calculated for each list and used to allocate seats to each list in each of the five electoral regions.