What's to question? He called a Democrat hack a monkey. It's a non-issue. An apology isn't necessary.
Still, it's not a good thing to do politically. It doesn't matter what he said or who he said it to. Someone running for office shouldn't call someone a name while campaigning lol.
I have an Indian friend, and he sends out email jokes about Indians and India every day. Every reference to a person's characteristics is not "racist". Sometimes it's just light hearted.