Founded by Cuauhtémoc Cárdenas Solórzano, Heberto Castillo, Gilberto Rincón Gallardo, and other leading left-wing politicians, it was proclaimed to be the party of the 6 de julio (July 6), referring to the date of Mexico's 1988 presidential election. On that date, it is alleged that Cárdenas, the candidate of a coalition of center-left parties, the Frente Democrático Nacional or FDN, won the election but was denied victory by fraudulent means. (Victory was instead given to the PRI candidate, Carlos Salinas de Gortari.)
The party traces its pedigree to the Partido Comunista de México (PCM, the Communist Party of Mexico), Partido Socialista Unificado de México (PSUM, the Unified Socialist Party of Mexico), and the Partido Mexicano Socialista (PMS, the Mexican Socialist Party). The PMS donated its registry with the Federal Electoral Commission (CFE) to enable the new party to be established. A large number of defectors from the PRI also swelled the PRD's ranks.
The PRD has a strong electoral presence in central Mexico. The party has won gubernatorial races in states including Michoacán, Zacatecas, and Baja California Sur. It has been responsible for both of the directly elected heads of government that the Federal District (Mexico City) has had since the office was created in 1997 and, in the 2003 local elections, 13 of the Federal District's 16 borough mayors (jefes delegacionales) were elected from among PRD candidates.