After Republican presidential nominee Donald Trump criticized a federal judge for his Mexican heritage, former House speaker Newt Gingrich called the billionaire’s behavior “inexcusable.” Gingrich, who has been a long-time supporter of Trump, said on Fox News Sunday that it was “one of the worst mistakes” the orange-hued demagogue has made in the 2016 campaign. Gingrich pointed to the fact that Judge Gonzalo Curiel was born in Indiana. “He is an American. Period,” Gingrich continued. “Trump, who has grandparents who came to the U.S., should understand this as much as anybody.” Trump has said that Curiel’s roots are an “absolute conflict” and that he may be biased because of Trump’s calls for a border wall.