Conversation so far:
What types of things was Linus Pauling criticized for?
Linus Pauling's critics, including scientists who appreciated the contributions that he had made in chemistry, disagreed with his political positions and saw him as a naïve spokesman for Soviet communism.
Who opposed Linus Pauling's works?
Linus Pauling's peace activism, his frequent travels, and his enthusiastic expansion into chemical-biomedical research all aroused opposition at Caltech.

Question: What political positions made him unpopular?
Self-contained rewrite: What political positions made Linus Pauling unpopular?