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.
Party of the Democratic Revolution
The Party of the Democratic Revolution (PRD, ) is a social democratic political party that had been one of the three major political parties in Mexico over the last several decades, the others being the Institutional Revolutionary Party (', PRI) and the National Action Party (', PAN).