Institutional Revolutionary Party
The Institutional Revolutionary Party (, PRI) is a Mexican political party founded in 1929 that held uninterrupted power in the country for 71 years from 1929 to 2000, first as the National Revolutionary Party (, PNR), then as the Party of the Mexican Revolution (, PRM), and finally renaming itself as the Institutional Revolutionary Party in 1946.
Socialist Mexican Party
The PMS was founded in 1987 through the merger of the Unified Socialist Party of Mexico, the Mexican Workers' Party, the Communist Leftist Union, the People's Revolutionary Movement and the Revolutionary Patriotic Party.