Final answer:
Senator Joseph McCarthy, a Republican from Wisconsin, led unsubstantiated communist witch-hunts during the early 1950s. He claimed to have a list of Communists in the federal government but never provided evidence, leading to the term 'McCarthyism' for such groundless accusations.
Step-by-step explanation:
During the early 1950s, Senator Joseph McCarthy, a Republican from Wisconsin, catapulted to infamy by initiating a series of unsubstantiated communist witch-hunts. In a period saturated with Cold War anxiety, McCarthy exploited the fears of the American public by claiming that the federal government was riddled with Communists. In a notorious speech delivered in Wheeling, West Virginia, McCarthy brandished a piece of paper, allegedly containing the names of 205 State Department employees who were supposedly Communist party members. As pressure mounted for him to reveal names, McCarthy's figures fluctuated wildly. Ultimately, he never presented any concrete evidence to back his claims, yet this did not prevent his accusations from escalating a national paranoia known as McCarthyism, which refers to the practice of making accusations of subversion or treason without proper regard for evidence.
McCarthy's witch-hunt not only aimed to expose alleged Communists but also to undermine the Democratic Party by suggesting that they had permitted Communists to infiltrate the federal government. His tactics included unjust indictments, which sowed distrust and fear, ultimately damaging reputations and careers. McCarthy's influence persisted until his censure by the Senate in 1954, which marked the decline of his political career and the waning of the red scare fervor he had fueled.