He was a lieutenant commander in Baltimore when, in September 1945, a group of Whittier Republicans asked him to run for Congress. He jumped at the opportunity, was mustered out of the Navy in January 1946, and began his victorious campaign. Nixon's friends described him as a mild and tolerant human being, basically shy and much influenced by his Quaker upbringing. Yet in all his early campaigns he conducted what he himself has described as "a fighting, rocking, socking campaign." He early infuriated the opposition. Though he called himself a liberal Republican and a progressive Republican, he had strong right-wing support. In his congressional campaign he had attacked his liberal New Deal Democrat and onetime Socialist opponent as a tool of the Congress of Industrial Organizations (CIO) and an enemy of free enterprise. As a member of the House Un-American Activities Committee (HUAC), Nixon became a leading anti-Communist crusader. He collaborated on the bill requiring Communist-front organizations to register with the attorney general. It was on HUAC that he first attracted national attention when he led the suit that resulted in the conviction of Alger Hiss, a former State Department official charged with Communist connections; Hiss was finally convicted for perjury. Nixon again aroused the enmity of liberals and intellectuals in his 1950 victorious senatorial campaign. He charged his Democratic opponent with displaying a "soft attitude toward communism" and said that she was part of a small clique that voted "time after time against measures that are for the security of this country."

It was thus as a fiery crusader against communism and a staunch Republican partisan that Nixon was known to the country when Gen. Dwight Eisenhower chose him as his running mate in the presidential election of 1952. Nixon's personality and character became permanent issues in all his political campaigns. He seemed to overuse political hyperbole and oversimplify complex issues. Some critics believed his fascination with political techniques showed lack of principle regarding substantive issues. Two months after becoming Republican vice-presidential candidate, Nixon was charged with being the beneficiary of a fund, totaling $18,235, collected from private citizens. Nixon said the sensational controversy resulted in "the most scarring personal crisis of my life." Nixon fought back. In a television speech that accounted for the money, he convinced his foes that he was artful and tricky, but he rallied Republicans to his banner.