Truman’s domestic policies on internal security were in part responsible for establishing a political atmosphere in which what would later be called McCarthyism was established. Fear of an international conspiracy created an overly simplistic answer for a whole set of very complex problems.
Truman early on replaced University trained intellectuals at the core of New Deal policy makers with senior military officers, top corporate level executives from the world of business, and old guard urban machine Democrats. Because of this the people Truman surrounded himself with came into government with a strong anti-communist bias. They saw any social democratic, social unionism or civil rights activists as people needing to be watched very closely. The fear of communist influence for possible dissenters was beginning to be discussed by mid-1946 even before the disastrous November elections. Tom Clark was already advising Truman along these lines. This along with Truman’s course of action in dealing with Communism in Europe and Soviet troops stationed in much of Eastern Europe gave the President an edge in mobilizing support for his foreign policy and limiting dissent. The Truman administration used the Communist threat, as it’s major crusade to mobilize support within the US to establish a U.S. presence around the world.