Not to beat a dead burro, but let's check: How has the Great Immigrant Backlash of 2006-2007 affected the GOP? The folk hero of the movement, Hazelton, PA Mayor Lou Barletta, has lost his challenge to mummified Democrat Paul Kanjorski. I don't recall a single public poll that showed Kanjorski winning. But he did.
The Democrats have gained two Senate seats in the Southwest, in Colorado and in New Mexico, as those states fell to Barack Obama (along with Nevada). At this hour they look to have picked up one House seat in Nevada, one in Colorado, one in Arizona, and two in New Mexico, all while losing nothing from their 2006 sweep in the area.
It's yet more evidence that immigration restrictionism is terrible politics. On this, Karl Rove was right.