The latest public hand wringing about illegal (and to some extent, legal) immigration has things exactly backwards.
By pushing illegal immigration further underground, whether by border patrols or by instituting new national IDs, the rights of the immigrants are reduced. A person without proper papers is at the mercy of the employers. In addition the cost of obtaining false papers goes up as well.
The result of all these pressures is to lower the amount of money immigrants can earn. This lowers the costs of their employers. But, the biggest losers are the legal workers who are competing for the same positions. A legitimate worker is forced to compete with someone who cannot really negotiate his pay scale.
So while conservatives may think that they are preserving jobs for "Americans" there is a high probability that existing workers will actually suffer.
This is easy to confirm, since there is very little support from business for increased immigration control. We continue to be in the hypocritical position that we object to immigrant labor, but demand the low prices that such labor can enable. Where are the "Americans" lining up to take these jobs?
We depend upon the underground workforce and pretend otherwise.