Complex sentence: He also supported Henry Wallace's Progressive Party and so many openly Communist organizations that he was accused of being a member of the Communist Party, and was a top target of the American government during the peak of 1950s McCarthyism.
Split into simpler sentences: He also supported Henry Wallace's Progressive Party and so many openly Communist organizations that he was accused of being a member of the Communist Party. He was a top target of the American government during the peak of 1950s McCarthyism.