What does the author suggest by using the word “rhetoric”? Who was Johnson saying was “free at last”?

Yet all Johnson’s rhetoric could not entirely disarm the suspicions of civil

rights advocates. (Roy Wilkins* asked him) if he had felt so strongly about the
issue, why had it taken him so long to act on it? Johnson wrinkled his brow and
said: “You will recognize the words I’m about to repeat. Free at last, free at last.
Thank God almighty, I’m free at last.”... Johnson was describing himself as
liberated from his southern political bonds or as a man who could now fully put
the national interest and moral concerns above the political constraints imposed
on a Texas senator.