Final answer:
Senator Joseph McCarthy's claims spread through his assertive and fear-inducing speeches during the early 1950s, leveraging the era's anxieties about communism. The extensive media coverage and his position in the Senate amplified his influence, but numerous inconsistencies and the lack of evidence eventually led to public disenchantment and his political demise.
Step-by-step explanation:
Senator Joseph McCarthy's claims began to spread in February 1950, when he delivered a speech in Wheeling, West Virginia, alleging he had a list of card-carrying Communists within the State Department. Despite not having such a list, the tactic of accusation without evidence became politically advantageous and was later called McCarthyism.
Through fear and the political climate of the Cold War, his baseless allegations gained traction in the U.S. National media coverage and McCarthy's position in the Senate helped to amplify his claims, even as the numbers of supposed Communists shifted. The lack of any proof did not deter McCarthy at first; his rise was marked by unsubstantiated charges and fear-mongering.
However, public opinion began to turn following the Army-McCarthy Hearings in 1954, which were broadcasted to millions, exposing McCarthy's bullying tactics and lack of evidence. Prestigious journalist Edward Murrow's critique and satirical portrayals in political cartoons also played a part in the public's waning support for McCarthy. Ultimately, McCarthy was censured by the U.S. Senate and his influence diminished thereafter, leading to his political downfall.