Senate campaign
In his campaign, McCarthy attacked La Follette for not enlisting during the war, although La Follette had been 46 when Pearl Harbor was bombed. He also claimed La Follette had made huge profits from his investments while he, McCarthy, had been away fighting for his country. In fact, McCarthy had invested in the stock market himself during the war, netting a profit of $42,000 in 1943. La Follette's investments consisted of partial interest in a radio station, which earned him a profit of $47,000 over two years.
The suggestion that La Follette had been guilty of war profiteering was deeply damaging, and McCarthy won the primary nomination 207,935 votes to 202,557. It was during this campaign that McCarthy started publicizing his war-time nickname "Tail-Gunner Joe", using the slogan, "Congress needs a tail-gunner". Arnold Beichman later stated that McCarthy "was elected to his first term in the Senate with support from the Communist-controlled United Electrical, Radio and Machine Workers, CIO", which preferred McCarthy to the anti-communist Robert M. La Follette. In the general election against Democratic opponent Howard J. McMurray, McCarthy won 61.2% to Democrat McMurray's 37.3%, and thus joined Senator Wiley, whom he had challenged unsuccessfully two years earlier, in the Senate.