Donald J. Trump is in the middle of a “policy speech” on immigration as I write this blog.

I want to focus for a moment on the Republican presidential nominee’s quick trip to Mexico City, where he met with Mexican President Enrique Pena Nieto.

He didn’t mention something that’s been a hallmark of his presidential campaign: getting Mexico to pay for building that “beautiful wall” across our southern border.

Trump’s initial — and signature — campaign pledge was to stop illegal immigrants. He vowed to build that wall. He then vowed in the next breath that Mexico would pay for it. “I’ll make Mexico pay for the wall,” he told his cheering supporters.

Well, he had President Pena Nieto in the room today. He didn’t bring up Mexico’s tab. How come?

Pena Nieto later restated his view that Mexico isn’t going to pay for the wall.

What did Trump accomplish by accepting this invitation to visit President Pena Nieto? I’m trying to figure it out.

No word of an apology for the insults Trump has hurled at the Mexican government for suggesting that “Mexico is sending” career criminals into the United States. Then again, Trump doesn’t apologize for anything.

Now, let’s hear what Trump has to say about how “I alone” will fix the nation’s immigration policy.