Leech was elected as a Republican to the Seventieth, Seventy-first, and Seventy-second Congresses and served until his resignation on January 29, 1932, having been appointed a member of the United States Board of Tax Appeals (now the United States Tax Court) to fill a vacancy. He was reappointed in 1934 and again in 1946, and served on this court until his death in Chevy Chase, Maryland. Interment in Lloyd Cemetery in Ebensburg.