The 1955 coup that removed peron began a lengthy period of instability in Argentine politics that lasted until 1983, with nineteen presidents in twenty-eight years. Competitive regimes and dictatorships alike were subject to rapid erosion and breakdown.
After three years of military rule(1955-58), Argentina returned to competitive politics in 1958 when the military government withdrew from power and sponsored elections. Even though the elections represented a fair contest for the candidates allowed to participate, they were marredin terms of democratic principles by the proscription of the Peronists. The duros within the armed forces and their civilian allies including aprominent part of the UCR preferred the radical suppression of Peronists. Moreover, the virulent anti-Peronism of President Pedro Aramburu contributed to Peronist radicalization.
If they had been allowed to run, Peronists would have won the elections an outcome that was unacceptable to the actors of the coalition that overthrew Peron in 1955. Because of the proscription of the largest party, the competitive regime established in 1958 was born with a congenial defect. The conservative’s fear of Peronism was a huge contributing factor to what O’Donnell called “the impossible game”: no government, whether authoritarian or semi-democratic, could create a stable governing coalition from 1955 to 1973.