Of the anti-Romney ads I've seen from both Republicans and the Democratic National Committee, this-from Jon Huntsman-might be the most brutal:
The striking thing is that this isn't hard to do at all. If you include 2005, the year he began to prepare for a run in earnest, Mitt Romney has been a presidential candidate for the last six years. And in his quest to prove his conservative bona fides, he's reversed himself on almost every issue under the sun. It's no exaggeration to say that anyone with an Internet connection, a video editor, and an hour of free time could make an ad like this.
Of course, the Huntsman ad doesn't have much circulation outside of those who follow politics for a living. If there's anything that will do actual damage to Romney's campaign, it's the disastrous Fox News interview that Huntsman sampled for his ad. By simply asking questions about Romney's prior views, Bret Baier exposed him as a man willing to say anything for the sake of elected office.
I've said this before, but it's simply true that Mitt Romney is a weak candidate whose flaws are masked by both the sorry state of his opposition, and his ability to execute the routine of campaigning without incident. When you put him under the spotlight and remove the crutch of routine (for instance, debates), as you can see in the interview, he becomes petulant, evasive, and uncomfortable. When you combine this with his medicore skills as a retail politician and the deep mistrust he inspires among Republican voters, it's easy to see how he remains vulnerable to a challenger, despite his solid position in the field.
Put another way, if Romney were faced with an actual competitor-former Florida Governor Jeb Bush comes to mind, as does former Arkansas Governor Mike Huckabee-I have no doubt that he would be trailing as the underdog. As it stands, there's a fair chance that he'll win the nomination by default.