Given that the rise of the alt-right wing of the GOP has been building since 2010, I have to believe that Romney might have a 3rd party more conservative challenger. Also, Democratic enthusiasm could be higher, as Hillary is the sort of challenger to defeat a sitting president by virtue of her experience, historic candidacy, and experience. I think it would be a very close race, with a Cruz-type republican taking enough support away from Romney to keep it a tossup til the very end.
No need to repeat yourself.
Was blanking on the 3rd reason, oops! </Perry>