I'm not the biggest fan of Richard Cohen, but you should read his attack on Mitt Romney's character, or lack thereof, in today's Washington Post. In a few sentences, he gets to the heart of Romney's persona - a mercenary politician who treats principles as a means to greater power:
Mitt Romney runs for president with the eye of a venture capitalist. He sees the profit in certain positions, discards those that are no longer profitable and moves on. He was pro-choice when it did him some good, instituted a health insurance plan that he now denounces and once supported amnesty for some illegal immigrants. Richard III offered his kingdom for a horse. Romney offers his principles for some votes in Iowa.
Ideological flexibility is par for the course in politicians, and there's nothing wrong with it - success in politics depends on a willingness to compromise, bend principle, and take deals when you can make them. Romney's core problem is that he takes this to its reductio ad absurdum. It's not just that Romney is willing to bend his principles for the sake of partially realizing them, it's that he adopts and sheds principles for the sake of narrow political advantage.
The push for health care reform in Massachusetts is a great illustration of this. Benjamin Wallace-Wells explains in his New York Magazine profile of the former governor, "Romney did not begin with a philosophical quest to improve American health care. He began with the idea of himself as a problem solver and asked those around him for a problem that he might usefully solve." As seems to be the case with everything else in his career, Romneycare had less to do with a particular vision of government's role in public life, and more to do with Romney's ongoing effort to build the "Romney" brand.