After the January 1964 "coup" against Khánh, Phát was made the commander of III Corps and also Interior Minister for a time until he was dismissed in September 1964. This prompted him to join Dương Văn Đức, another general relieved of command, in launching a coup attempt against Khánh on 13 September. They initially took over the capital without a fight, but Khánh escaped, and after having received endorsements from the U.S., defeated Phát and Đức. At the military trial that followed, charges were dropped. In February 1965, Phát joined with fellow Catholic, Diệm "protégé" and Khánh opponent Phạm Ngọc Thảo – actually a communist agent intent on maximizing infighting in South Vietnam – in another "coup" attempt. After the forces deadlocked, Phát met with Republic of Vietnam Air Force chief Nguyễn Cao Kỳ, insisting on Khánh's assassination. After the meeting concluded, the coup collapsed, but Khánh was forced from office the next day. Phát and Thảo went into hiding and were sentenced to death in absentia by Kỳ's military tribunal. Thảo was killed under mysterious circumstances, but Phát evaded capture for three years until surrendering. By this time Kỳ's power had been eclipsed by another Catholic, General Nguyễn Văn Thiệu, who freed Phát from prison.