During her brother José López Portillo's (1976-1982) presidency, she received sharp criticism for his nepotism and failure to act on warnings of potential fire at the National Cinema Library.
Her family was one of intellectuals and military officers, as her grandfather José López Portillo y Rojas had been a writer, was a member of the Mexican Academy of Language and one-time governor of the state of Jalisco.
[6] In 1976, after her brother, José López Portillo, was elected president, but before he took office,[7] Margarita was the victim of an attempted kidnapping by the Liga Comunista 23 de Septiembre, during which one of the leaders of the organization, David Jiménez Sarmiento, was killed.
[8][9] Upon assuming office, López Portillo made Margarita head of the General Directorate of Radio, Television and Cinematography (RTC), and she immediately reversed the policy of the previous administration.
[3] She was resoundingly criticized for her management of the RTC and when the Cineteca Nacional [es] burned and five people were killed in the fire of 24 March 1982, Margarita was blamed for not having heeded warnings of danger.
[3] She led an effort to restore the convent where the Sister had lived[2] and served as Chairman of the Board of the committee for preservation of Sor Juana Ines de la Cruz.