BOGOTÁ, Colombia — Venezuela said Wednesday that it would pull out of the Organization of American States, which has long been critical of President Nicolás Maduro’s unyielding accumulation of power at the expense of the country’s democratic institutions.

The move increases Venezuela’s isolation while its government is struggling to put down mass street protests demanding new elections. And it shows that the country — which, through anticapitalist rhetoric and oil largess, once aimed to challenge the United States as a power in Latin America — is becoming something of a pariah in its own region.

On Wednesday evening, Foreign Minister Delcy Rodríguez said Mr. Maduro had instructed her to break ties with the organization because of what she described as “intrusive, arbitrary, illegal, deviant and crude actions.” She added, “A faction of governments from the region had eyes on our sovereignty and tried to intervene and lecture our country, but this, fortunately, will not happen.”

The O.A.S., whose charter promotes democracy among member organizations in the Western Hemisphere, has become the principal body through which Venezuela’s neighbors have exerted pressure as concerns mount regarding the country’s stability.