Cárdenas immediately showed his independence by becoming the first Mexican president to campaign for office. Once in office, he began his sexenio by adopting several popular measures. He reduced his presidential salary and decided not to move into the national palace, he ordered a resumption of land reform on an unprecedented scale, and he expressed tacit support for a wave of urban strikes. Calles followed these developments with unease, and soon sought to undermine the new president's authority. A definitive break occurred between Calles and Cárdenas when the new president fired many of Calles's followers in the federal bureaucracy and closed down a network of gambling houses owned by Calles's associates. It became apparent that Calles had underestimated Cárdenas's commitment to reform and his political skills. Calles's open opposition to Cárdenas finally earned the former leader forced exile to the United States in 1936. Conservatives from San Luis Potosí staged a rebellion in protest, but the military remained loyal to the president and brought the revolt under control.