Answer: Institutional Revolutionary Party (Partido Revolucionario Institucional, PRI).
The Institutional Revolutionary Party is the political party in Mexico which dominated most of the twentieth century. It held the power uninterrupted from 1929 to 2000, and then again from 2012 to 2018. The party was founded in 1929 by Plutarco Elias Calles, self-proclaimed "Supreme Chief" of the Mexican Revolution. The party had changed its ideology several times throughout its history. Nowadays, it is mostly considered a centre-right party.