Conversation so far:
Who was the running mate of Hubert Humphrey during the 1968 presidential election?
Edmund Muskie was Hubert Humphrey's running mate.
who were the protesters during the 1968 presidental election?
Protesters of the 1968 election included young college students, which amplified the growing feelings of unrest in the general public.
Where did Hubert Humphrey win the Democratic nomination?
Hubert Humphrey won the party's nomination at the Convention on the first ballot, amid riots in Chicago.

Question: What are the factors that caused his loss at the election to Nixon?
Self-contained rewrite: What are the factors that caused Hubert Humphrey loss at the election to Nixon?