Opinion writer
Wisconsin Gov. Scott Walker, left, pauses while preparing to speak to the media at the Iowa State Fair in Des Moines. (Daniel Acker/Bloomberg News)

Since immigration has once again become a prominent issue in the GOP race, candidates should be carefully questioned in the next debate. Here’s a start:

Yes or no: Do you support repealing birthright citizenship?

If it requires amending or repealing the 14th Amendment, would you do so?

Would you apply it to children of illegal immigrants already here? If so, are you prepared to treat them as non-citizens? How would you determine who is and is not a citizen?

If you don’t apply it retroactively and the borders are sealed under your plan, what is the purpose of getting rid of birthright citizenship?

After e-Verify, border security, visa overstay and other measures are implemented, do you support forcible deportation of those who remain? Would you split up families?

How much would that cost? How would you pay for it?

Do you support reducing legal immigration? Do you think the United States should refuse high-skilled workers who want to come here?

What evidence do you have that immigration of high-skilled workers depresses U.S. wages? Aren’t there many studies that show the opposite?

If you don’t remove illegal immigrants by force, what would you do with them?

Does immigration increase GDP? Does it increase tax revenue? Does it help correct the demographic problems with retirement programs (because immigrants are younger)?

Is the Mexican border the biggest problem in immigration enforcement?

There is value in discussing these issues in depth because the anti-immigration crowd is generally unprepared to accept ownership for the drastic steps that would be necessitated by their policies. It is easy to see why: Anti-immigration extremism is in conflict with the Constitution (as currently drafted), “family values,” fiscal prudence and common sense. In other words, it is not conservative at all. As Nick Gillespie reminded us, support for a Trump-like approach requires leaps of logic and a dearth of humanity. In addition to the police-state measures needed to round all these people up, there is all this:

Let’s forget simple facts like the reality that immigrants, especially illegals, go to where unemployment is lowest; that immigration, whether legal or not, is a boon to the larger economy; that illegals are already barred from virtually all sorts of budget-busting welfare and that they commit crimes at lower rates than native-born folks. Here’s a thought experiment: Imagine the parts of the country that are worst-off economically. Now go check out whether they are destinations for migrants of any kind, whether legal, illegal, or from other parts of the United States. Without exception, you will find that the hardest-luck parts of the nation are those without high levels of in-migration.

It’s not surprising that Trump buys into all this — or doesn’t care about the real world — but it is dismaying when a governor running for president, a distinguished conservative magazine and many Republican voters (although nowhere near a majority) say they approve. Sober candidates such as Sen. Marco Rubio (R-Fla.) and Jeb Bush dismissed the idea of repealing birthright citizenship (Ohio Gov. John Kasich does not support the idea either), correctly identifying that the idea as not grounded in reality. Carly Fiorina likewise rebuffed the idea.

It’s virtually impossible to imagine that anyone seriously supporting a Trump-like plan would make it to the Oval Office. If Republicans want to gain back the White House, they’d be wise to pick from candidates not aping Trump.