McCarthyism in the 1950s is most closely associated with <em><u>Wisconsin Senator Joseph McCarthy.</u></em>
Explanation:
Joseph McCarthy was a key figure during the early years of the Cold War. He was one of the first American political figures, and easily the most vocal one, to publicly state that Communist sympathized had infiltrated the United States government.
His nation-wide fame brought about the term 'McCarthyism' a practice where any can be labelled as a traitor and communist without any evidence.
