Immigration and Terrorism
But he isn't proposing that, and neither is anyone else. As they surely all know, illegal immigrants to the U.S. are typically from Latin America or East Asia, not places with large Muslim populations. Increasing their numbers may be a good or bad thing, but it isn't going to promote terrorism.
The remaining argument, always left vague, is "control of our borders." Presumably the theory is that an Al Queda operative is going to fly into Mexico, get himself smuggled across the Rio Grande, take a bus to Washington D.C. and blow something up. Why he should go to all that trouble when the U.S. has over fifty million legal foreign visitors a year is never explained. Does anyone believe that our customs agents can spot the terrorist needle in that haystack?