 In the aftermath of the Mexican Revolution (1910-1920), the Constitution of 1917 set the legal framework for the Mexican government.Revolutionary generals dominated politics in the 1920s and 1930s.With the assassination of former general and President-elect Alvaro Obregón in 1928, former general and out-going President of Mexico, Plutarco Elías Calles, founded a political party, the Partido Nacional Revolutionario (PNR), to solve the immediate political crisis of the assassination and to create a long term framework for political stability, especially the transition of presidential regimes.