The Cold War can be said to have lasted from 1945 to 1991.  During this time, political conditions in the United States certainly did not remain static.  Therefore, there were many different political conditions during the Cold War.  The only thing that was really constant the whole time was that there was some amount of pressure on American leaders to be strong in their opposition to communism.  There was not always the same amount of this pressure, but it was always there to some degree.  Essentially no major American political figure during the Cold War could ignore the danger of looking to be too "soft" with regard to communism.