Simple. Latinos are the fastest-growing minority demographic in the US. The Republicans are courting the Hispanic vote like Romeo after Juliet. They've made great headway with the Cubans in Florida, and are now looking to break into the Mexican mainstream as well. No way in Hades are they gonna do anything to rock this boat.
I live in Salinas, CA, part of the 38% non-Hispanic minority. A while back I was involved in a minor traffic accident, and the officer who responded said he was so amazed that the two parties actually called the police that he let us both go without tickets (we each deserved one.) He went on to say that about 80% of the traffic accidents in Monterey County are caused by undocumented drivers who just split before police arrive.
Our apartment building, in a very nice neighborhood only three blocks from the police station, just got tagged again, which means the other gang--both Mexican, of course--will be by to try to leave their mark as well. It's a constant problem. They paint, we call the city Graffiti Abatement team who remove it, they paint again. I'm really getting sick of this place.
From what I can see the GOP is totally beholden to corporate interests, in turn corporations are addicted to cheap labor. Dummycrats see potential votes, so the bottom line is neither party has anything to gain by stopping the tide.