This article describes and analyzes the formal and informal processes of selection used by the Popular Party and by the Socialist Spanish Party in order to determine the person who would be the candidate to the Presidency of the Government of Spain in the elections of March 2004. The comparison allows us to state that, in spite of foreseeing different forms, in both cases a low level of internal party participation was found. To preserve the internal cohesion
and to strengthen the leadership of parties, three approaches were taken: the centralization of decision making, the elimination of effective competition between candidates and reduction of the number of the participants in the selection process.