POLITICAL REVOLUTIONARY PARTY
Partido de la Revolución Democrática (PRD)

The Democratic Revolutionary Party, or PRD, split away from the ruling PRI in 1988 and has since become a legitimate political force in Mexico in short time. Former PRI member, Cuauhtémoc Cárdenas, founded the PRD in 1988 to offer Mexico a center-left platform, including increased government control of the economy, expanded social welfare and opposition to foreign trade and investment.

In 1997, Cárdenas was elected mayor of Mexico City. The position is considered Mexico's second most-powerful -- and like many candidates before him, Cárdenas hopes to use it as a stepping stone to the presidency. Though he lost his bid in 1988, Cárdenas is a candidate again in the upcoming election. His father, Lázaro Cárdenas, was also an elected president.

As a PRI member, Cárdenas pushed for an end to "tapadismo," the presidential selection of the party's nominee without a vote. A little more than a decade later, the PRI is holding its first primary presidential election.