My criticisms of his health care speech aside, Mitt Romney had a good weekend. Mike Huckabee announced he isn’t running. Newt Gingrich shot himself in the foot by attacking Paul Ryan and defending the individual mandate. Sarah Palin hasn’t taken any steps toward running. With the field shaping up the way it has so far, Romney has to be considered the clear frontrunner.

It’s possible Gingrich can overcome his gaffe this weekend. Pat Buchanan successfully became the top candidate to the right of Bob Dole in 1996 after criticizing the congressional Republicans’ attempt to cut Medicare. George W. Bush became the nominee despite going after congressional Republicans for “balancing the budget on the backs of the poor” in 1999. But unlike Gingrich, both waited until after the congressional GOP had already lost those battles before piling on. Moreover, it’s hard to see how Gingrich goes anywhere without getting to Romney’s right, and if there is anywhere to get to Romney’s right, the individual mandate is the place to do it.

Ramesh Ponnnuru makes an interesting case that Tim Pawlenty could threaten Romney and Michele Bachmann could keep anyone to Romney’s right from winning the nomination. But both Pawlenty and Bachmann still need to bypass Gingrich, Donald Trump (assuming he actually runs), and Ron Paul to play their hypothetical roles. How they do in Iowa will obviously be key.