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.
Mexican People's Party
In 1981 PPM and other left-wing parties merged to form the United Socialist Party of Mexico (PSUM). However, in January 1985 a faction of former PPM members Led by Alejandro Gascón Mercado broke away from PSUM. This group founded the Party of Socialist Revolution.