Why do anti-illegal immigrant folks want to overturn the case law on immigrant rights and federal supremacy?

American immigration law is mostly based on racism. It was enacted when white Protestants feared that an influx of Southern and Eastern Europeans (i.e. Catholics and Jews) was diluting the "racial purity" of the US. We see much the same feelings directed today against Hispanics. As for the Constitution, the right in this country loves to wave around the "original meaning" when it suits their position (such as the right to bear arms). When their positions don't match the Constitution, they have no problem tossing it aside (for example the desire to revoke the citizenship by birth right).