sentences:  With the support of the revolutionary army, the Sonoran generals' Plan of Agua Prieta successfully challenged Carranza's attempt to perpetuate his power; Carranza was killed as he was fleeing the country.De la Huerta became interim president of Mexico and Obregón was elected president for a four-year term, 1920–1924.As Obregón's four-year term was ending, Calles bid for the presidency.