The video: Mitt Romney is starting to slap GOP presidential rival Newt Gingrich as an inconsistent conservative. But Rep. Ron Paul (Texas) has already thrown a hard right hook. Paul — who needs to beat Gingrich in the Jan. 3 Iowa caucuses — released a hard-hitting, anti-Gingrich web ad this week, then smacked the media for giving Newt "a free ride" on his shifting positions. "He's a flip-flopper, so he can hardly be the alternative to Mitt Romney," Paul said. The damning web ad (watch it below) goes much farther. In the video, Newt is accused of "serial hypocrisy" on issues like health care reform and climate change, and is branded as "the very essence of the Washington insider" for pocketing more than $1 million from Freddie Mac. "Everything that Gingrich railed against when he was in the House," says an unseen political commentator, "he went the other way on when he got paid to go the other way."

The reaction: This ad is "a direct hit" that makes an easy "mockery of Gingrich's act as a Washington outsider and populist," says Brent Budowsky at The Hill. It works because it's true, and because the principled Paul is a "credible" messenger. But this video doesn't make me want to vote for Paul, says Allahpundit at Hot Air. It just makes me "despair over the state of the race." Some Republicans who "basically like both men" are surprised by this "gleefully vicious video," says Ben Smith at Politico. But remember, Paul the "purist" and "the compromising Gingrich" have never seen eye to eye, and their feud goes back more than a decade. Watch for yourself: