Mexican Revolution
The PRI, or Institutional Revolutionary Party is one of the major lasting legacies of the Mexican Revolution; its first iteration was the Partido Nacional Revolucionario founded in 1929 under Northern revolutionary general and president of Mexico (1924–1928) Plutarco Elías Calles, following the assassination of president-elect (and former president) Álvaro Obregón in 1928. The establishment of the party created an enduring structure that managed not only presidential succession but also groups with competing interests. Initially, Calles remained the power behind the presidency during a period known as the Maximato, but his hand-picked presidential candidate, Lázaro Cárdenas, won a power struggle with Calles, expelling him from the country. Cárdenas reorganized the party that Calles founded, creating formal sectors for interest groups, including one for the Mexican military. The reorganized party was named Party of the Mexican Revolution. In 1946, the party again changed its name to the Institutional Revolutionary Party. The party under its various names held the presidency uninterruptedly from 1929 to 2000, and again from 2012 to 2018 under President Enrique Peña Nieto.
Plutarco Elías Calles
Under Calles's rule in 1926, a constitutional change was passed that allowed for a non-consecutive re-election, and in 1928 Obregón was elected as Calles's successor; this amendment was later repealed in 1934. In addition, Mexico passed an amendment to the constitution in 1927 that expanded a presidential term from four years to six years. However, Obregón was murdered by José de León Toral, a Catholic militant, before he could assume power. To avoid a political vacuum, Calles named himself "Jefe Máximo", the political chieftain of Mexico and Emilio Portes Gil was appointed temporary president, although in reality he was little more than a puppet of Calles. The following year, Calles founded the National Revolutionary Party (, PNR), the predecessor of today's Institutional Revolutionary Party (, PRI).