If Hillary successfully exploits the "immigration issue", it will be because there are people who normally vote GOP who think of Mexicans as inevitably Democrat voters, don't like Mexicans, don't like their culture, don't like their social conservatism, are appalled that we now receive 45% of the ENTIRE Hispanic vote (which means a probable majority of Mexicans already given the hevily Democratic allegiance of Puerto Ricans) and the fact that many who regard themselves as conservatives are very favorable toward welfare state programs so long as those programs are only for people like themselves. You're applying the race baiting bit thickly this close to the New Year.
If Hillary successfully exploits the weakness President Bush threatens to bring to the GOP if he is able to legalize any illegal aliens, it will be because a few per cent of swing voters, who aren't lockstep Republicans, flipped their votes her way.