I think Clinton has it the easiest. If she wins Iowa, I think she would win New Hampshire and South Carolina and run the table. If Obama were to win Iowa, he'd have the momentum too, but Clinton might could put up a fight still. Edwards can win Iowa and both Clinton or Obama could successfully challenge him in NH since he just doesn't do well there. There you might see the greatest possibility of a delegate fight happening. It would suck for Democrats, but as an objective political observer it'd be pretty damn interesting!