The contemporary party system in Mexico is relatively young. For 70 years, the entire political scene was shaped, and therefore dominated by a single party: the PRI. The two major opposition forces barely consolidated as such when achieving their first electoral victories in the 1990s; since their birth, they have been forced to play by the rules established by the PRI. Consequently, they have adopted similar strategies to the ones of the PRI for allocating candidacies to the federal congress, and to secure electoral victories at the regional and local levels. These consist of resorting to local leaders of the party and affiliated sectors to select those candidates with the most convenient background for the organisation’s interest. Due to constitutional prohibition of immediate re-election at the federal and state levels, parties compete for power through the use of loyalties and clientelism, which results in entrenched internal conflicts – factionalism-, disengagement with the electorate and the lack of professionalization of politicians. This paper argues that the historical evolution of the three main parties in Mexico – the PRI, the PAN and the PRD- and the Mexican political context – where formal rules are frequently overridden by informal practices-, have led to dominant parties with multiple strong leadership figures and hence an evident shortcoming in developing into stable and representative institutions; they are clearly unable to fulfil the electorate’s expectations. Extracts from an empirical case study showing the criteria for candidate-selection, party switching and committee appointments in the 60th Federal Congress (2006-2009), shall serve as supporting evidence of the nature of parties and the extent of their power. This paper will conclude that the Mexican case is one where political parties are far from successfully performing the institutional and representative roles that, in theory, they are supposed to play. The democratization process of the country has made them unable to link the society with the state.
