He split from Democratic Action in 1967 when it tried to prevent his victory in district-level primary elections for the 1968 presidential race translating into Prieto Figueroa winning the nomination.

He and a substantial group of supporters split from AD and founded the People's Electoral Movement, which he led until his death.

[1] He was a founding member of party Acción Democrática (AD, Democratic Action), and minister of education under Rómulo Gallegos (1947-8).

[4] Prieto Figueroa split from AD over the affair along with a substantial number of his supporters, founding the People's Electoral Movement.

However Prieto's subsequent electoral run, in the 1978 Venezuelan presidential election (the party endorsed Jesús Ángel Paz Galarraga in 1973), achieved only just over 1%.