As Hagel, who is the conservative that everyone pretends McCain is (note I said "conservative" and not "some guy liberals should love because he's secretly liberal"), says, the whole Guard-on-the-border-plan is stupid. My guess is that there isn't a real plan to do this, just a plan to stage some elaborate "border security theater" and give Bush some chances to play dress up while hunting Mexicans. Hell, didn't Rove say as much at some point? There won't really be any kind of actually serious border enforcement program, it'll just be yet another way to exploit the hardworking people of the National Guard as political props.
Won't help them though. I was worried about the immigration issue for awhile, even knowing the Republicans were going to screw it up. But I think, somewhat surprisingly, that America's xenophobic streak isn't quite as strong as I had thought. In addition I don't see that people are connecting whatever economic angst they have very strongly with the immigration issue.