Donald Trump’s signature issue in his quest to become president of the United States?

I guess it’s immigration.

What is his idea? Round up all 11 million — maybe it’s more — individuals who are here illegally, send them back to their native country. But, he says, do it “humanely.”

OK. How do we do that?

Well, he wants to hire about 25,000 additional federal employees — let’s call ’em immigrant wranglers. He’d deploy them across the country to hunt down those who are here without proper documentation. They’d take the immigrants into custody, I reckon, process them and then send them back to their country of origin.

Someone has to start taking Trump seriously to task for continuing to promote an idea that is looking more and more like utter insanity.

Has anyone figured out the cost of an operation that Trump is proposing? And what in the world does this mean to those who want a smaller federal workforce? Trump is proposing growing the federal payroll by at least 25,000 individuals. And does he consider this to be a one-time operation, that them immigrant wranglers will round up the undocumented immigrants one time, call it good and then move on to other jobs?

Not all GOP candidates have endorsed Trump’s nuttiness. “We all know you can’t pick them up and ship them … back across the border,” Ohio Gov. John Kasich said. “It’s a silly argument. It is not an adult argument. It makes no sense.”

Oh, I almost forgot. Trump is going to build a “beautiful wall” stretching from the mouth of the Rio Grande River in South Texas all the way to the Pacific Ocean, just south of San Diego, Calif. That’ll keep the illegal immigrants out. Job finished.

Hillary Rodham Clinton said this about the Trump Plan: “The idea of tracking down and deporting 11 million people is absurd, inhumane, and un-American. No, Trump.”

Let’s add “insane” and “idiotic.”

This is the leading Republican presidential candidate’s formula for “making America great again”?