You might be an Obama fan because you regard him as at least better than Bush.
You might be an Obama fan because you believe that in his heart of hearts he wants to do the right thing.
You might be an Obama fan because you think that a black president is a major step forward for this country.
You might be an Obama fan because you think that the GOP and the Tea Partiers are a major threat to the nation and the world and that their enmity for Obama and their desires to get rid of him makes it necessary for you to stand by him and the Democrats, suppressing or muffling any criticisms you may have to him and/or the Democrats.
You might not be an Obama fan, but are unsure of what else there is to be.
To all of you, I have one thought experiment to offer you: