Okay, Nixon died fairly recently and all the presidents since him are still alive, so that leaves Johnson and earlier. Kennedy? Maybe, but I'm guessing Truman. Much earlier than that and I'm getting awfully close to when I expect you'd be too young to have cared much for being interested in presidents, but I'm guessing as to your age (and assuming that has anything to do with it).

Ooh! No! Wait! It has to be Warren Harding! Potentially more mealymouthed than our current Parsident.