Unprincipled ambition.

That's how Charles Blow describes Mitt Romney. From his piece in the Times (my emphasis): 

Infinite malleability is its own vice because it’s infinitely corruptible by others of ignoble intentions. 

Not only has [Romney] at some point in his political life been on both sides of more issues than I have energy to list here, he has made clear during the primaries that he is willing to shift to the far right on far too many issues to be the right president for modern America.