Low-skill low-education employment is most threatened by migrant labor. Shifting tax calculations to favor off-shoring and legalizing free trade with Mexico was going to fuck every blue collar worker out there; if I can put in a spectacular tile floor for $400 but two guys you pick up outside Home Depot can put in a mediocre tile floor for $50, you're going to have a mediocre tile floor and I'm going to have trouble feeding my kid and while I should blame you? I am also going to blame the guys outside Home Depot and the politicians who made this possible. Capital has long known that if you focus blue collar workers on the migrants, rather than the policies, they'll keep voting your way.
Although I think they have mostly just rediscovered that if you don’t provide the voters any choice at all and both parties have nearly identical policies then politicians don’t even have to bother with even that. There really hasn’t been any meaningful immigration reform in the last 20 years and I don’t foresee any progress in at least the next decade