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 party participated solely in the 1988 elections, in which it had postulated Heberto Castillo as its candidate. A month before the elections, Castillo decided to decline his candidacy in favor of Cuauhtémoc Cárdenas Solórzano and integrate himself in the National Democratic Front that postulated Cárdenas to the Presidency of the Republic. In 1989, after the electoral process had finished, the PMS integrated with the old Democratic Current of the PRI and constituted the Party of the Democratic Revolution, with the own legal registry of the PMS.