IMO we should start beating the libs at their game - deciding what the terms are that are to be used to describe things. In this case illegal aliens. They are not undocumented immigrants. They are criminals that are invading our country.
If every single republican used the term "illegal aliens", and refused to use or accept the use of "undocumented immigrant", that alone would help shape the debate. Everytime a leftie says it, respond with illegal alien in some fashion.
I have no problem using the word "alien" - the Bible doesn't either.