Although a majority of Americans oppose illegal immigration regardless of who's involved--it is true that many of us oppose even legal immigration by Mexicans. That makes us racist, right?
That's the accusation leftists use to stop debate by changing the subject from the principles to character assassination.
Here's the trick, though: we do feel differently about Mexican illegal immigrants, but it's not racism. It's the fact that uniquely among illegal immigrants, Mexicans have been taught from birth to believe that the American Southwest is actually part of Mexico and we Americans have no right to it (something many American leftists heartily agree with). Moreover, Mexicans generally dislike America, and Americans, and American culture (as substantiated by opinion polls). That isn't unique among immigrants (I personally know some Russian immigrants who don't seem to think much of American either). But it's a lot more common among Mexicans.
Why should I welcome immigrants--illegal or not--who don't like me or my country? My immigrant friends from other countries (such as Belarus, India, South Africa and the former East Germany) still appreciate their home countries, but they also love America. And they don't believe they deserve a place here--they believe they have to work to earn that place.
That's the kind of immigrant I want here. Of course there are Mexicans who don't feel entitled and who do love America, but I get the impression they're a minority. And we already have so many more Mexicans than any other kind of immigrant, I'd be happy to put a halt to even legal immigration from Mexico of unskilled laborers for the foreseeable future--including "family reunification." Families are welcome to reunify in their country of origin.