Who was the Republican senator known for investigations into alleged communist activities in the U.S.?

The Republican senator known for his investigations into alleged communist activities in the United States is Joseph McCarthy. He became synonymous with the anti-communist sentiment of the early Cold War era, particularly during the 1950s. McCarthy conducted a series of hearings that aimed to expose alleged communist infiltration in the U.S. government and other institutions. His aggressive tactics and often unfounded accusations led to a significant impact on American society and politics, instilling a pervasive fear of communism known as McCarthyism. This period was characterized by heightened paranoia regarding communism and the belief that communists were attempting to undermine American values and institutions.

In contrast, Richard Nixon was more famously known for his role in the Watergate scandal and his foreign policy initiatives during his presidency rather than primarily focusing on anti-communist investigations. Barry Goldwater is recognized for his conservative ideology and candidacy in the 1964 presidential election, while John McCain was known for his military service, long political career, and efforts towards bipartisanship but did not engage in the same level of anti-communist investigations as McCarthy.