When we lived in SA, the people who most disliked the illegals were the legal Mexicans. And they were pretty vocal about it, saying if they could do it legally and come here to work, so should the ones sneaking in at the border.
And that is exactly the way I feel-granted, my family came from Spain to what was then also Spanish territory, but they did it legally-they bought a permit to settle, and passage on a ship, like everyone from Europe did at that time...
Some of the most vocal about illegal immigration are ranchers and other people who live in SW Texas, near the border, like my family-they absolutely loathe mojados.