The procedure for selecting candidates can be regulated by the rules of the electoral system of a territory, both by special laws and the Constitution. Some countries introduced legislative reforms in this matter during the last decades, so as: Costa Rica, Honduras, Colombia (1994), Peru (2003) and Dominican Republic (2004).

These rules can promote more competitive designations, through primary processes, or they allow that the designation corresponds to the organic mechanisms of political parties. In the case of holding internal elections, following Freidenberg (2003), and Payne et al. (2003: 173), it can be said that “the rules differ depending on:

1. a) the number of actors involved in the electoral process, if they are open elections – where all citizens can participate – or closed elections – where only participating party members.
2. b) According to the timing of the elections: separate – each party carries out their elections on dates different – or simultaneous – all are made the same day.
3. c) If they receive public funding or not.
4. d) If there are organizational involvement or supervision by the electoral management body”.

Candidate selection is the most important and critical moment in the day to day of political parties. Success or failure of the party, This designation will depend, largely, and with it, its institutional role and their share of power, as well as its ability to influence the political agenda. For this reason, getting a nomination is considered a resource to key in a partisan organization, in particular, when its members win elections becomes the goal primary1 and the appointment as a candidate means the perspective a political office (Kirchheimer, 1980: 344).