Folks here seem to be missing that Perry is allowing Mitt to appear to move to the right of him, especially on immigration.
After watching tonight, Perry is done, long-term, which leaves Mitt as the only announced candidate with a chance at the nomination. Watch.
Better late than never Sam. 
But Perry is the best thing that ever happened to Mitt. He gets a chance to appear adult, and more knowledgable, and nuanced, again and again, while Perry and Bachmann and Santorum chew each other up. I'm sure Mitttens hopes they all stay in through Florida. After that, it's over.
Oh, one other thing: as each drops out, they will endorse Mitt.
Most GOP voters don't want somebody who appears "adult, knowledgable and nuanced" even if you do.
