democrats stand up for the corporate interests that push for cheap labour. they directly represent capital, and it's bourgeois class (which identifies with "progressive values", including the idea that challenging the status quo of cheap racialized labour is racist).

republicans create a distraction for disaffected workers, which prevents them from revolting against capital and feeds into the progressive narrative. they blame everything on brown people, which divides the working class against itself.

so, they work together, rather than against each other.

there is not a mainstream option that has the interests of workers - migrant or native - in mind.