This is a big self-inflicted wound by Perry. Before he was getting beat up just for mandating HPV inoculations (pretty petty stuff). Now Perry has given this opponent something serious to run with. If I had to guess on which ones Republicans hate more: Obama's healthcare law or illegal immigrants, I'd have to say it's illegal immigrants.
Perry has done Mitt Romney a great favor, shifting the debate off of his support of the individual mandate onto Perry's heartless comment.
This is really starting to look like the end for the Perry campaign. Given Perry's sliding poll numbers, it's starting to look like Romney is again emerging as the front-runner, with his opposition divided among the far right.
That's ultimately good for the GOP, as Romney is probably more electable.