It's not in the public domain since copyright's are still in effect. And all commercial use licenses for music, be they from ASCAP or whoever, have an exclusion for political events. But even if he did have the right to, why would Trump or any other candidate want to use a song if the performer didn't want them to?
Thanks for the update. So, is the band that was/is playing allowed to play some of the songs live? Now that is plagiarism. LOL!