It says here that anti-immigration activists are/have been attempting to take over the Sierra Club so they can deliver their [expletive deleted] message in a seemingly innocuous and ostensibly "liberal" wrapper. Grumble.
For more information, check out this link at the Southern Poverty Law Center's Intelligence Report web site: Hostile Takeover.
For the record, while I believe it as reasonable and permissible to discuss immigration concerns as it is to discuss environmental concerns, I don't believe is it appropriate to mix the two; I think it's even less appropriate to hijack one discussion to make points about another.