As for Eisenhower himself, Welch characterized him, in words that have made the candy manufacturer famous, as “a dedicated, conscious agent of the Communist conspiracy” — a conclusion, he added, “based on an accumulation of detailed evidence so extensive and so palpable that it seems to put this conviction beyond any reasonable doubt.”

Richard Hofstadter (1916–1970) American historian and intellectual

“The Paranoid Style in American Politics,” Herbert Spencer Lecture, Oxford (Nov 1963)
    (Source)

Reprinted in Harpers (Nov 1964).