Democrats want the illegal migrants here for the votes; Republicans want them here for agri-business and other industries. Individuals in both parties who are on board with the whole "new world order" thing and the "AU" want them here as well. A complete betrayal of their oaths.
UPDATE: "Cheap labor is essential..." Factor in the costs of higher insurance costs, higher taxes, the costs of incarcerating these illegals, the costs of educating their children, the fact that most of them pay no federal income taxes, etc...and tell me that this is offset by "cheap lettuce".