If he knows you really well, and you had a class or two with him and performed well, then it's fine. If you're just going to get a LOR from him because he's the University President, and you'll most likely get a letter saying "To whom it may concern: I'm the President of my University. Bruner is a student here. He's a good student.", then I'd say you should find another prof who can write a more detailed, positive rec.