In
1938, McDowell defeated incumbent
James L. Quinn for a seat in the
Seventy-sixth Congress, but was defeated after a single term by
Samuel A. Weiss. He lost to Weiss in a rematch in
1942. In
1946, McDowell defeated
Harry J. Davenport for a seat in the
Eightieth Congress by just over 1,100 votes. It was a relatively narrow victory for a reliably Republican district. McDowell served on the
House Un-American Activities Committee (HUAC) in 1947 and 1948 and was acting chairman when
J. Parnell Thomas was not presiding. In early 1948, he argued against granting a visa to boxer
Max Schmeling, who wanted to stage a comeback in the United States. The
State Department later denied Schmeling the visa in that he did not meet any of the categories for granting visas to German citizens. Later, he played a role in the
Alger Hiss case. The key witness,
Whittaker Chambers, was asked to provide details about Hiss that few people would know. He mentioned that Hiss was a birdwatcher and had bragged about seeing a
prothonotary warbler. In the hearing
Richard Nixon asked Hiss about his hobbies, to which he replied tennis and amateur ornithology. McDowell interjected with a question as to whether Hiss had ever seen a prothonotary warbler, to which Hiss gushed in the hearing that he had indeed, seen one, and described it to the committee. This helped persuade the committee that Chambers was being truthful. On March 16, 1948, McDowell introduced a bill to grant the
Speaker of the United States House of Representatives or the
President of the United States Senate the power to obtain secret documents from any government agency. McDowell stated: The day before, U.S. President
Harry S. Truman issued an executive directive, which barred Congress from just that. In October 1948, after indictments against 12 suspected communists in what would become the
Foley Square trials, US Attorney
John F. X. McGohey called on McDowell to appear before a grand jury in the case after McDowell charged that prosecutors deliberately drew up the indictments in such a way that the charges would not result in a conviction. McDowell later called McGohey and Attorney General
Ramsey Clark "inept" in producing the indictments. In the
1948 election, Harry J. Davenport avenged his 1946 loss and defeated McDowell's bid for re-election. ==Personal life==