According to Juan Williams, Christie only will get in if it looks like Palin is getting in, setting himself up as the anti-Palin, since she would be unstoppable against the current field:

What will it take to get Chris  Christie to say yes and run for the GOP nomination?

Come on down — Sarah  Palin.

If the queen of the Tea  Party makes a grand entrance into the Republican primary sweepstakes the New Jersey  governor will finally say yes to all the calls for him to jump into the race….

All the talk about Palin has the Republican political establishment seeing red.  They fear losing control of the nominating process and the whole party spiraling  down, sinking into a sea of far-right polarization and the cult of personality  around Palin if “Sarah Barracuda” – her nickname as star high school basketball  player — swims into their waters and begins eating up Mitt  Romney, Rick  Perry and the other current Republican candidates.

Williams’ theory — and I don’t know if it’s anything more than that — makes sense:

None of those [poll] numbers will matter if Palin gets in the race.  She will become a media sensation. The rest of the field will be an  afterthought. That is the moment when the Republican political establishment  will send out the call for the one remaining political star on the GOP side who  can take the spotlight away from Palin. That candidate is Gov. Christie.

The only way for Christie to get out from under his promises and suicide threats not to run is to claim that the world has changed.  Which it would have if Palin gets in.

The problem with Christie’s strategy of waiting for Palin is that Palin keeps waiting, while Christie keeps promising he’s not running.  A late entrance by Palin will make her look tactically astute, while a reactionary late entrance by Christie will make him look like a reactionary late entrant.

[Note: “?” added to title because it’s just Williams saying it for now, although it makes sense to me.]