He was mayor of his hometown from 1983 to 1991, and regional congressman in Asturias from 1983 to 1987. Masip was first involved in Spanish politics during Franco's dictatorship (being a member of the opposition Frente de Liberación Popular—"Felipe"), and then being a member of the Spanish Socialist Workers' Party since 1979.
He was one of the first lawyers in Asturias to defend workers outside the Francoist vertical trade unions in the early 1970s. In 1979 he defended the accused of the Holy Chamber's Jewels theft (during which traditional 10th century Asturian symbols like the Victory Cross, Angel's Cross and Agates' Box were stolen).
1983: Chairman of the Institute of Asturian Studies
Vice-President of the Prince of Asturias Foundation
1982-1987: Member of the Asturian Regional Parliament
Author of several books (including Oviedo al fondo, Desde mi ventana, De Oviedo a Salinas por el Eo and La sirenita y otros coletazos) and other works (including Indalecio Prieto y Oviedo, Apunte para un estudio de la Guerra Civil en Asturias, La última reunión del Consejo Soberano de Asturias y León, La autodeterminación del Sáhara Occidental, Alegaciones al Estatuto de Autonomía de Asturias, Asturias en las ediciones de 'Voyage au bout de la nuit' de Céline and El pintor Luis Fernández)