The Revolutionary Party of the Nationalist Left was a left-wing political party in Bolivia. It was founded in 1963 by the labor leader Juan Lechín Oquendo and by Mario Torres Calleja and Edwin Moller in lesser roles. The PRIN seceded from the Revolutionary Nationalist Movement (MNR) in protest against Víctor Paz Estenssoro's decision to seek a third elected term as president in 1964, rather than permit then Vice-President Juan Lechín to have the MNR's presidential nomination.