IT'S NOT AS IF EVEN THE NATIVISTS ARE SERIOUS ABOUT IT:

A "federal dragnet" capable of snaring all the undocumented immigrants in the U.S. over five years would cost about $200 billion, according to the pro-immigration (and liberal) Center for American Progress -- assuming that 20 percent of them would depart voluntarily once the effort got started.

The pro-immigration (and conservative) American Action Forum is less sanguine. It reported that a combination of forcible and voluntary deportation would cost $420 to $619 billion over 20 years. Meanwhile, real gross domestic product would decline by 5.7 percent, or almost $1.6 trillion.

Provided that most Americans become willing to see the economy shrink and to shoulder hundreds of billions in additional government spending, deportation policy makers could move on to the logistics of removal. Along with funding, this is an excellent topic for Thursday's Republican presidential debate. What other candidates support mass deportation? How do they propose to address questions such as:

Considering that about 3.5 million undocumented immigrants reside in the U.S. with at least one U.S. citizen child under age 18, what should happen to these children when their parents are sent across the border?

Removing millions of largely Hispanic residents will ruffle the sensitivities of some foreign nations and human-rights groups; how should the U.S. handle the diplomatic fallout?

Some undocumented immigrants don't just work in the U.S.; they employ others. How should ownership of their enterprises be awarded? Or should the businesses simply be shut down and their employees dispersed?

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