Hi Charlie, I honestly don't think you have a whole lot to worry about. In the US, the foreign-born fraction of the population rose from 4.7% in 1970 to 10.4% in 2000. The primary effect of this has been to completely marginalize the nativist right. Bush #2 is known to be sympathetic to the idea of open borders with Mexico, and he's about as right-wing as mainstream American politicians come.

One really weird dynamic you need to watch out for is the mating of the anti-immigration with environmentalist rhetoric. A lot of the anti-immigration rhetoric in the US is now coded green. You'll get ignored as a crank and a racist if you talk about teeming hordes crowding out natives, but recode it with talk about how population increase threatens the environment and increases urban sprawl, and suddenly it sounds mainstream. It's very icky.