What would a Mitt Romney...

...presidency look like? David Frum offers a cautionary tale (his emphasis): 

If Romney wins, the first challenge he will face is a contest with Congress to determine who will control the GOP agenda. Romney will have to exercise caution to protect himself —not only against the general electorate—but also against his own party. A President Romney will arrive in office with very few instrumentalities of power. His congressional party will believe that he rode their coat tails into office. They spent the prior two years writing an agenda for him, and they'll expect him dutifully to execute it—at least until they receive some shock from the voters that jolts them into fear of over-reach. But they won't learn that fear from President Romney.