Primary elections in Argentina are called "PASO". The acronym stands for "Primarias Abiertas Simultáneas y Obligatorias" (Spanish: Simultaneous and mandatory open primaries). They were established in 2011 by the law 26,571.
With this system, all parties run primary elections in a same general elections. All parties must take part in it, both the parties with internal factions and parties with a single candidate list. Citizens may vote for any candidate of any party, but may only cast a single vote.
Parties must also get 1.5% or higher of the vote to be allowed to run in the main elections. 149 minor parties were either closed, or were not allowed to run in specific provinces where they did not met the requirements. This was rejected by the oppositions, who charged that these reforms could stymy minor parties and the formation of new ones.
Private funding for political campaigns is not allowed. All parties are granted free airtime during the political campaign to air advertisements, of a fixed time duration.
Primary elections also serve as polls for the actual presidential elections, revealing the number of votes that the candidates may receive in them.