again: you're going to have a hard time pinning me down into a partisan position on this, because i denounce both parties equally. i don't believe in borders, and i'd like to erase them from the map. but, i'm staunchly critical of the democrats for upholding what is essentially a system of slavery, designed to maximize profits for corporate farmers, while keeping prices low for consumers. this is not a just system, and should not be maintained.
if you think you're standing in solidarity with migrant workers by standing with their employers, you're either a delusional idiot or you're a fascist asshole. these people are underpaid, they're not protected by labour rights, they face massive abuses and they are often void of basic civil rights in the process. i don't use the term lightly - they are enslaved.
making the issue about immigration is a cop-out. the issue is about labour rights, and standing in solidarity with the workers - not with the employers - means standing up for their rights to collective bargaining, to fair wages, to safe workplaces and to everything else that workers fight for and largely get in the united states and in canada. they are not lesser than us, and they should not be treated as though they are - they deserve the same rights as us.
now, it follows that if you were to actually enforce all of these things then mexican labour would lose it's absolute advantage. if employers had to pay all of the same things for imported labour that they do for domestic labour, imported labour would just have added costs attached to it. this would increase the competitiveness of domestic applicants; it would even the playing field.
but, that's just a corollary to the basic point, which is that a legitimately leftist position means standing in solidarity with the rights of workers, and not with the rights of corporations or the rights of consumers.
i don't know what he's doing, so it's hard to analyze. but, it's not clear to me that a ban on foreign workers is a worse idea than the status quo is.