Former House Speaker Newt Gingrich said in a radio interview on Monday that Donald Trump's attack on a federal judge's heritage goes against "being an American" and goes down a road that will destroy America.

Trump has said U.S. District Judge Gonzalo Curiel, who is overseeing a civil fraud lawsuit against Trump University, has a conflict of interest in the case because of his "Mexican heritage" and membership in a Latino lawyers' association.

On the The John Gibson Show on Monday, Gingrich said, "Well, first of all, what we know about general numbers and about an individual are, it totally goes against our whole model of being an American."

"We don't judge you as part of a group," continued Gingrich. "That would be to suggest blacks can't get a fair white judge, whites can't get a fair black judge. Asians can get a fair judge unless they're Asian and by the way, Asian means if you're Chinese, it has to be a Chinese judge because Vietnamese, while they're Asian, aren't Chinese. Once you go down that road, you destroy America."

"So you can't take a group definition and apply it," said Gingrich. "If there are things this judge has done that are wrong — and I think there are — you know you can pound him into the ground as a judge who did the following things. But that's taking on an individual, it's not taking on an entire ethnic group."