A smart move for Christie would be to let the other candidates split the hardcore conservative votes and he can pick up all the moderates. If he doesn't even get into the polemics he can pick up enough votes that he will be the presumptive candidate. I hold out hope that the primary voters still know a winner when they see one and will vote for him regardless of his refusal to descend into the bloodbath for the ultraconservatives (Romney couldn't benefit from this because Romney was always too stiff and artificial, hence the long fight with a candidate with no chance of winning).

Also, don't forget that Hillary may have her own problems if Elizabeth Warren chooses to run, since most people outside the left wing of the Democratic party may have some issues with how far to the left she is.