Nope, Romney would have lost huge, hate to break your bubble, but the guy who’s ineptitude brought us Gay Marriage as a national issue, and government fiat mandatory health care or go to jail, had no chance to win a national race. You can’t run around claiming the mantle or Reagan after governing under the mantle of a Todd Witman.
Romney couldn’t even win the primaries of his own party, and was only alive as long as he was due to spending his own money on it.