And if that doesn't work. Then it would be time to put the military on the border and shoot anyone trying to sneak in.
What I would NOT do... is say that we are under dire threat from Islamic terror groups and FAIL to do anything. I would not say that SS/welfare/medicare is in dire trouble while shoveling money out to illegals.
I think it might be better to turn them away at the border --- but instead of shooting them --- hand them each a gun. Show them the movie The Patriot before sending them back --- they really need to do something about the elites trying to get them out of their own homeland.