The immigration issue won't help Bush --- not much with hispanics either. I don't know if you've followed Cesar Chavez --- who is considered a hero to many Chicanos --- but he was anti-immigration. The UFW were even on the border working with border patrol to stop immigration from Mexico ---many hispanics actually believe Bush is just helping the elites by keeping wages down --- their wages. It might not be fair --- but the democrats know how to play that issue on both sides. Maybe because they have the naive and gullible voters.
I don't doubt, however, you are correct that the rats will certainly stoop to anything.
I don't want to leave the impression that I think Dubya will gain votes through the immigration issue. I believe most Americans if asked will say they are for tighter immigration controls, but most of them don't care enough to change their vote one way or the other. I see no evidence that Dubya's pro-immigration stands will harm him. A commitment to expanding the H1B quota did not prevent candidate Bush from becoming President but a commitment to close the border and limit trade may have destroyed Buchanan's chances in 92, 96, and 2000. I have sited Davis and Richardson as examples of rats not hurt by Pro-trade/pro-immigration(They go hand in hand IMO) stances. I can also point to Rohm Emmanuel in Chicago.