Following the October Revolution and the rise of Bolsheviks to power in Russia, tensions between the reformist and the revolutionary factions of Argentina's Socialist Party (Partido Socialista, PS) reached its breaking point.

He was also responsible for organizing local NKVD agents in Spain and directing the persecution, torture, and murder of militant anarchists, members of the Workers Party of Marxist Unification, and other opponents of the PCE in the International Brigades.

The party actively supported the Soviet Union during World War II by organizing aid collections and having its leaders contribute to various international tasks under the orders of Moscow.

As a result of the workers' mobilizations of 17 October 1945 against the dismissal and detention of Juan Domingo Perón, within the party there were questions to the political line of the same and to the leadership headed by Codovilla and in the National Conference of December of that year, Rodolfo Puiggrós openly expressed criticism and demanded to find practical agreements with Perón around the defense of the interests of the workers and the fight against imperialism.

[4]On 17 June 1955, the police of Rosario arrested, tortured and disappeared Juan Ingallinella, a doctor and party leader, who had participated in the publication of pamphlets in defense of the government days before, denouncing the masterminds of the bombing and strafing of the Plaza de Mayo, in which more than 350 people were killed and more than 700 wounded and mutilated.

The Central Committee of the PCA 27 28 did not condemn the coup d'état of 1976 and the consequent military dictatorship established at the beginning.26 29 30 31 32 A few days after the coup, an official publication of the PCA affirmed with respect to the new president: "Regarding his more precise formulations ... we affirm emphatically that they constitute the basis of a liberating program that we share .... he affirms that no easy, miraculous or spectacular solutions will be given, be assured that nobody expects them ... General Videla does not ask for adhesion, but understanding, he has it ".33 This position was based on a political characterization that "presented the Videla-Viola duo as the wing of renewed democracy, in front of a Pinochet wing, a non-predominant sector within the Armed Forces, channeled through Emilio Massera and Luciano Menéndez" and coincided with the support that the government of the Soviet Union offered the military dictatorship.31 26 This characterization was not easily accepted by all its militancy, which, between internal discussions, was distributed among those who trusted the word of the leaders and those who preferred to act for your account or refusing to accept directions from the addresses.34 The PCA was not affected by laws 21,322, 21,323 and 21,325 that dissolved some parties and left groups; its activity was suspended and, according to the report of the IACHR, like nine other political parties, it was subjected to "flexible government behavior" and was received in interviews by the military government.35 Despite this, a large number of PCA militants were persecuted, tortured, murdered and disappeared during the dictatorship.

Alberto Nadra affirms that the accusations made by the PCA before the IACHR allowed for the first time this organism to assume the existence of "state terrorism" in Argentina, taking as "pilot case" that of the student Inés Ollero, as well as the detention of almost 1,600 militants, the kidnapping of more than 500 and the murder of 150, show the objective resistance to the dictatorship, regardless of the public position of the PC.

In taking stock of this period on the occasion of the 30th anniversary of the coup d'état, the PCA issued a statement in which it stated: "each force in its own way, it cost us all to understand the novelty of the dictatorship imposed by the Yankees and supported by a vast political and social space ... We made mistakes in assessing the internal contradictions of the Armed Forces, overestimating them and considering taking advantage of them in the fight against fascism.

We are not, as we know and we do not hide, an infallible force neither in the sayings nor in the behaviors, but we are proud of belonging to a party that resisted the attacks of the dictatorship with dignity and that gave its contribution to the solidarity struggle from the first day, in the interior of the country and also in n the outside ".