In 1936, Jensen, a Republican, defeated incumbent Governor Tom Berry as South Dakota Governor. He served from 1937 until 1939. During Jensen's single term as governor, the legislature created a state department to implement the new federal Social Security Act. In addition, despite the financial demands of the relief effort, the Jensen administration was able to balance South Dakota's general fund and eliminate a twenty-year-old overdraft as well as to reduce the state's bonded indebtedness and provide for refunding of rural credit bonds at lower rates of interest. In 1938, the South Dakota Division of the Motor Patrol was formed under Governor Jensen. Harlan J. Bushfield, former Republican state chairman, succeeded Leslie Jensen as governor.