Conversation so far:
Who was Hubert Humphrey's running mate during the 1968 presidential election?
Edmund Muskie was Hubert Humphrey's running mate.
Was Hubert Humphrey an anti-war candidate?
No, Hubert Humphrey was not an anti-war candidate.

Question: Who did he lose his second term to?
Self-contained rewrite: Who did Hubert Humphrey lose his second term to?