Even after Barrientos' death, Guevara Arze continued as Bolivia's ambassador to the United Nations under Presidents Luis Adolfo Siles Salinas and Alfredo Ovando Candía, until 1970.

[8] In the 1978 and 1979 presidential elections the Authentic Revolutionary Party supported Víctor Paz Estenssoro's candidacy for the presidency, with Guevara Arze as his running mate in 1978.

The two weeks which followed were perhaps Guevara Arze's finest as a statesman; he vigorously opposed Alberto Natusch Busch and helped rally civilian and military opposition to the colonel's ruthless rule.

That post went to Lidia Gueiler Tejada, a dissident leader of the Revolutionary Party of the Nationalist Left, who had also backed Víctor Paz Estenssoro in the 1979 general election.

The Authentic Revolutionary Party has little popular following or basis for existence beyond Guevara Arze's personal ambitions and prestige, and it is chiefly useful for backstage maneuvering and coalition-building.