Every sign points to a Romney win tonight, but the real story will lie in his margin of victory. If he barely ekes one out,his challengers will have a renewed rationale for pushing on with vigor.
But if Romney wins in a romp, exceeding the combined percentages of the second and third place finishers or coming close, he moves forward with even greater strength -- and his challengers lose the argument that a single non-Romney challenger could meaningfully change the dynamic of the race.
It will also be interesting to see how much the quasi-endorsement of Gingrich by Sarah Palin and the endorsement of Herman Cain ends up mattering. One could argue that Governor Palin has a fair amount riding on Newt Gingrich's performance tonight.