 Originally a Democrat, Kelley was elected to the South Dakota House of Representatives in 1890 and 1891.He later joined the Populist Party, and ran unsuccessfully for the United States House of Representatives in 1892 and 1894.In 1896 he was elected to Seat A, one of South Dakota's two at-large U.S. House seats, and he served in the 55th United States Congress, March 4, 1897 to March 3, 1899.