1. Rob Portman
2. Scott Walker
3. Hillary Clinton
4. Jeb Bush
5. Joe Biden (ascending to the Presidency due to some horrible event)
Obviously if by some miracle Hillary doesn't run then all bets are off.
What? You think Rob Portman, a guy who very well may not even run and would likely lose the primary if he did, is more likely to be elected president than the nearly certain Democratic nominee?
Yes and Portman may very well run, he's just been smart enough not to paint a giant target on his back. I actually think he'll probably be the Republican nominee if he runs (and I'd be beyond shocked if Hillary beat him).