I may never forgive Donald Trump for what he said about Mexicans. I may never forgive him for what he said about Muslims or that smutty crack he made about Megyn Kelly. I may never forgive him for his lies and his bravado and his nasty personalizing of political differences. I may never forgive him for all these things, but I draw the line at Serge Kovaleski, the reporter with a congenital condition that limits mobility . Trump mocked him. I will never forgive him for that.

This happened in November, and I’m sure you know about it, but it has been left in the dust kicked up by further Trump outrages that include a denial that he ever did what in fact he did. He twisted his body in approximation of Kovaleski’s. Trump not only denied doing it, but he denied knowing about Kovaleski’s condition, despite having been interviewed by him on several occasions.

Kovaleski now works at the New York Times, but he was once a colleague of mine at The Post. I used to see him in the vast newsroom and wonder about him and admire him as well. His disability, called arthrogryposis, is instantly noticeable. It forces him to hold his arms in a distinctive way.

My guess is that he could have done anything he wanted. He’s a graduate of the College of William and Mary and talented enough to have worked at two of the best American newspapers. He could have been a lawyer or an accountant or a hedge-fund honcho — you name it. What I’m saying is that he could have made a pretty good living sitting behind a desk and not, on a daily basis, confronting people who are unprepared for his appearance. Every day as a reporter, he must see the double take of the surprised.

Trump’s other outrages arguably had an element of political calculation to them. The stuff about Mexicans, about immigrants in general, and about Muslims was popular among his supporters. It’s not that I think these insults were disingenuous — the man’s bigotry was evident when he insistently questioned whether Barack Obama was a natural-born American — but they applied to large groups, momentarily unpopular, and no single person either had to bear a stigma or feel the hurt. Trump came closest to showing his innate cruelty with his remark that John McCain, who spent five years as a prisoner of war in Vietnam, was no hero. Trump has an adolescent’s contempt for the suffering of others.

With his recent victory in South Carolina, we have to face the prospect that Trump could be the Republican nominee, possibly the next president of the United States. It’s a depressing thought. He’s crass and dishonest, a bully in a bespoke suit. But he’s also cruel, as evinced by his crack about McCain and, more particularly, his mocking of Kovaleski. After all, McCain’s heroism is beyond question and a personal attribute. His captivity, his tortures, may not be fully behind him, but it is in the past. Not so Kovaleski’s condition. It’s with him every day.

Trump has his charms. But he’s a towel-snapper — a rich kid who has always had it easy. He has never had the character-building setbacks that sometimes season the callow — Franklin D. Roosevelt’s polio or Robert F. Kennedy’s loss of his brother John, for instance. These are the sorts of things that reduce the rich to the powerlessness of the poor. Trump has none of that. He lives in a pre-Copernican world of his own. The sun revolves around him.

Brett Duncan Smith, a University of Georgia student, drove 90 miles last week to see John Kasich in Clemson, S.C. Smith was distraught. A year before, the man “who was like my second dad, he killed himself,” Smith told Kasich. “And then a few months later, my parents got a divorce, and then a few months later, my dad lost his job.” Smith went on like this, and finally asked Kasich for a hug. The Ohio governor stepped forward and threw his arms around him.

I contrast Kasich to Trump not because I think the willingness to hug is the measure of a great president, but because empathy is. The cliche about feeling someone else’s pain cannot be applied to Trump. He does not appreciate the difference between fortunate and entitled. The only pain he feels is his own. He never apologized to Kovaleski and he never seemed to appreciate why he should. You may conclude that he’s merely rude. I think he’s dangerous.