The Fourteenth Amendment to the United States Constitution disqualifies as senators any federal or state officers who had taken the requisite oath to support the Constitution but who later engaged in rebellion or aided the enemies of the United States. This provision, which came into force soon after the end of the Civil War, was intended to prevent those who had sided with the Confederacy from serving. That Amendment, however, also provides a method to remove that disqualification: a two-thirds vote of both chambers of Congress.