While you may want to delete your post if he gets elected anyway, just because it will have outlived its usefulness, there is nothing wrong with expressing one's opinion of a political candidate. We have a First Amendment right to do that, and such speech is protected.
You would not have the right to say things that are untrue about someone and publish them. That could potentially get you sued whether the person you were talking about was a politician or not. You also cannot threaten someone, because that can be a criminal
offense if you put someone in fear of his safety.
But to tell why you do or don't like a political candidate at a time when on one level or another countless American's are doing something similar in an effort to influence the votes of others is not a criminal offense. If you look at a newspaper on any given day you will see reports of how one or the other was less than completely honest, etc.
Don't lose any sleep about it. This is not a crime against the state. It's no more than the type of thing all of us say, unfortunately, about all too many government figures, because there are things that have happened from which we can draw an opinion.