Answer
Plutarco Elías Calles, a prominent Mexican politician and military leader, was designated as the successor to Álvaro Obregón, the President of Mexico at the time. Obregón made this decision due to Calles's loyalty, political skills, and proven ability in various government positions. Calles would go on to play a significant role in shaping Mexico's political landscape and implementing social reforms during his presidency and subsequent influence in Mexican politics.