It is sometimes called a bubble or a boomlet or a bandwagon. A new political figure arrives on the national stage and audiences swoon. Suddenly, mysteriously, and without anybody knowing much about him, he is The One, the next hot thing, eclipsing all other presidential wannabes. (Until he isn't anymore.) This bubble is not love -- as anyone who was ever 15 years old can testify. This bubble is infatuation. Political infatuation. Presidential contenders can be the subject of crushes just as surely as that new kid in high school, and in both cases it's what you don't know about...