Ross Douthat wonders who there is on the Republican side capable of stopping Christie from winning the nomination:

It’s early yet, Christie is hardly a near-lock like the current Democratic frontrunner, and (as she well knows) even near-locks have been known to run and lose.

But still, I’d be more certain of his vulnerability if I had a clearer sense of who might actually beat him.

Christie’s main advantage in a nomination contest is that he will likely have no real competition for most moderate Republican voters, and these voters make up a significant portion of the electorates in early primary states. Like past relative moderates that have secured the nomination, Christie would probably benefit from having a number of conservatives vying with one another and splitting the conservative vote enough that he can eke out big primary wins early on. A large 2016 field filled with a half-dozen or more conservatives trying to become the movement-approved consensus candidate makes a Christie victory almost too easy to imagine, while a much smaller field of just four or five candidates makes it much more difficult. Conservatives have consistently failed to get “one of their own” as the nominee in recent elections because they were divided into four or five competing camps. The best chance of blocking Christie or any other relative moderate candidate is to have one or more other candidates running that can siphon off some of his moderate and “somewhat conservative” support. There are hardly any likely candidates that would fit that description, and they would have little incentive to compete in the same year as Christie. His re-election win will have the effect of discouraging other would-be relative moderate candidates from running. That is the argument for Christie-as-juggernaut in the 2016 race.

The case against a Christie nomination is that he is far enough removed from the rest of the party geographically and culturally that he will fall flat with most primary voters. Besides the obvious policy disagreements and cultural differences with conservatives around the country, the biggest obstacles Christie faces are that the party doesn’t usually nominate a candidate from the Northeast and conservatives are more skeptical of the “electability” argument than ever. Having heard the electability argument repeatedly over the last two elections and having seen both nominees go down to defeat, more conservatives are inclined to reject it than they used to be. Republicans obviously did nominate someone from the Northeast last year, so it’s conceivable that it could happen again, but there’s also considerable regret on the right about “allowing” Romney to become the nominee. Primary voters may take out their buyer’s remorse for McCain and Romney on Christie. Republicans haven’t nominated a Northeastern candidate and won a general election since the GOP ceased to be the dominant party in the region. Parties don’t normally choose nominees that come from regions where they are weakest, and the reason for that seems simple enough: politicians that are successful there are not a very good fit with the rest of the national party.

It’s certainly possible to stop Christie from winning the nomination, but if his opponents in the GOP want to make that happen they are going to need to start soon instead of waiting until the summer of 2015 and complaining about the lack of competitive alternatives.