López Portillo chose Miguel de la Madrid as his successor, and his presidency had no significant pro-democratic changes. Yet the federal government's failure to adequately respond to the 1982 economic crisis and the 1985 earthquake enhanced public discontent with the government. When de la Madrid chose Carlos Salinas as his successor, he upset the popular leftist Cuauhtémoc Cárdenas, son of President Lázaro Cárdenas, who expected to be designated the PRI candidate. Cárdenas was thus motivated to leave the PRI and establish the Partido Revolucionario Democratico (PRD) in 1989 as the second significant opposition party to the PRI. On election day, Cardenas appeared to be approaching victorious, but a breakdown of electronic ballot machines eventually gave Salinas a narrow victory. As the PRD gained electoral power in local elections throughout the 1990s, it adopted the PAN's strategy of using mobilization to extract concessions from the PRI, though their mobilizations were more spontaneous and local compared to their conservative counterparts. The PRI continued to grant concessions, viewing them as the only way to keep their opposition at bay. The first five years of the 1990s saw an increase in the filing of electoral complaints in courts, reflecting more victories for the opposition parties and the PRI's continued attempts to maintain power.