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.
Institutional Democratic Party
The PID was formed in 1963 by Enrique Peralta Azurdia after he had seized power in a coup. A centre-right party, it was modelled on the Mexican Institutional Revolutionary Party. From the onset the party was dominated by the country's military elite. Despite this the party maintained close links with individual civilian parties during its existence, with their civilian allies often outnumbering them in the Assembly.