The Union () was a heterogenous centre-left political and electoral alliance of political parties in Italy. The Union was the direct heir of The Olive Tree coalition which represented the centre-left in the 1996 and 2001 general elections. However, The Union also included parties of the radical left, which were not affiliated with The Olive Tree. The Union was led by Romano Prodi, Prime Minister of Italy from May 2006 to May 2008, and former President of the European Commission. Collapsing in the wake of the 2008 Italian political crisis, the alliance was succeeded by the current-day centre-left coalition. Parties 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. The Democratic Party (PD, social-democratic), a merger of DS and DL, replaced its predecessor parties as a member of The Union upon its foundation in October 2007, becoming the largest member party of the alliance. Also during that time, the SDI became the Socialist Party (PS). Primary elections As of 2005, the coalition was assumed to be led by Prodi, however he called for a primary election in order to gain an official leadership. 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. With the new majoritarian electoral system, two clear blocks emerged since 1996. The primary elections for The Union took place on 16 October 2005. Previous primary election in Apulia Primary elections had never been held on a national level before in Italy, and only once at a regional level, in Apulia: in that occasion, Nichi Vendola, a communist and gay Catholic, became the candidate for the centre-left coalition in a region reputed to be conservative and with deep religious roots. 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. Candidates When the primary elections were first proposed, they were mostly meant as a plebiscite for Romano Prodi, since there were no other candidates to the leadership of the coalition. The secretary of the Communist Refoundation Party, Fausto Bertinotti,