In that same year, he was nominated as a Republican to run for the United States House of Representatives seat for New Jersey's 8th congressional district.

[6] He was one of a relatively small number of Republicans to hold their seats throughout the Great Depression and World War II.

[9] Hartley soundly defeated Rudd again in 1938,[10] and won re-election in 1940 against William W. Holmwood,[11] in 1942 against Frederic Bigelow,[12] in 1944 against Luke A. Kiernan Jr.,[13] and in 1946 against his future successor Peter W. Rodino Jr.[14] Hartley found the level of postwar labor unrest to be very disturbing, and felt that it threatened both economic and political stability.

[15] With his party in the majority, Hartley served as the chairman of the Committee on Education and Labor in the 80th United States Congress.

[22][19] Labor allies failed to break the filibuster, and the repeal bill was withdrawn by the Democratic Majority Leader, Mike Mansfield, in 1966.

[23] Hartley did not seek any further election to Congress following the term in which the act which bears his name was passed, and his service concluded on January 3, 1949.