A conservative estimate on an immigration strategy like Newt's probably is worth 2-3% loss in support today in a GOP primary and practically all of that can be won back in not much time. It could likely result in no change.
Acceptance towards a real(not BS) comprehensive plan on immigration is rising with conservative voters. But for the most part its just showing up in people not willing to answer what happens after you have "secured the border" and "effectively stopped illegal immigration".
Well Cain's answer to secure the border is to "Secure the border" and everything will be saved. I'd like to know HOW people, to all the candidates. All they say is a fence, and that will magically ward off millions.