Later, he would move on to organized political parties, including the Partido Patriótico Revolucionario [es], where he directed its newspaper, Tribuna Proletaria.

After his first loss in Sonora, Zambrano Grijalva headed to the Federal District, a PRD stronghold, where he was the Public Defender (Procurador Social) from 1997 to 1998 and a delegation chief for Gustavo A. Madero from 1998 to 1999.

[1] In 2004, during the leadership of Andrés Manuel López Obrador, Zambrano Grijalva returned to the Federal District government, as an advisor, liaison to Congress, and coordinator of strategic projects.

During the LXI Legislature, he served as vice president of the Board of Directors and as secretary of the Mesa de Decanos, which groups the longest-serving federal legislators.

In 2011, Zambrano Grijalva was elected to be the new head of the PRD; he resigned from the Chamber of Deputies and Héctor Barraza Chávez served the remainder of his term.