The parties which were part of the coalition for most of the time are: DS, DL and MRE contested elections as The Olive Tree federation.

Primary elections were a novelty in Italian politics, as the proportional system in place until the early 1990s was supposed to present sufficient variety to electors.

The institute of primary election came under criticism from some centre-left moderates, as in their opinion it had produced a useless candidate doomed to failure.

However, Vendola's victory against the incumbent governor and centre-right candidate Raffaele Fitto, a much more conventional and moderate young man, vindicated the primary elections in the internal argumentations of The Union.

The secretary of the Communist Refoundation Party, Fausto Bertinotti, then announced he would run for the leadership, even if only to act as a symbolic candidate, to avoid a one-candidate election.

Francesco Fortugno, vice-president of the Council of Calabria and member of The Daisy (DL), was murdered on 16 October 2005 by two killers when he was waiting in line to vote in a polling station in Locri.