In
1922, when incumbent United States Congressman
Carl W. Riddick opted to
run for the Senate rather than seek re-election to the
United States House of Representatives, Leavitt ran to succeed him in
Montana's 2nd congressional district. He defeated Preston B. Moss, the
Democratic nominee, by a wide margin to win his first term, and in
1924, defeated Joseph Kirschwing by a landslide to win his second term. Leavitt was re-elected in
1926 against Harry B. Mitchell, was overwhelmingly re-elected in
1928 over B. A. Taylor, and won what would be his fifth and final term in Congress in
1930 over Tom Stout. On March 5, 1932, Leavitt took to the floor of the House to deliver a eulogy to Indian Chief
Plenty Coups. "I have chosen to announce the passing of one who has graced the history of my state of Montana," said Leavitt on the floor of the U.S. House of Representatives. [Plenty Coup's] life was in truth a symbol of the absorption of the American Indian into the citizenship of the United States," Leavitt continued. "His was one of the finest characters I have ever known.... He was a man of such caliber and such high character, and his service was so outstanding, that it is entirely fitting that the American Congress should pause for a moment to do him reverence. Leavitt ran for re-election in
1932, but was defeated by
Roy E. Ayers in a Democratic landslide year that saw Republicans lose over a hundred seats in the
United States House of Representatives. From the
69th United States Congress to the
71st United States Congress, Leavitt served as the Chairman of the
House Committee on Indian Affairs. Following his defeat for re-election, Leavitt ran for the
United States Senate in a
1934 special election to fill the seat of
Thomas J. Walsh, who died in office. He won the
Republican primary against former
State Attorney General Wellington D. Rankin, but lost the general election to
James E. Murray in a landslide. After his unsuccessful campaign for the Senate, he started working for the Forest Service again in
Milwaukee, Wisconsin, and served as the Commander-in-Chief of the
United Spanish War Veterans from 1936 to 1937. ==Later life==