Former Republican Speaker of the House Newt Gingrich (Ga.) called presumptive Republican nominee Donald Trump an “absurd amateur” during remarks at the 2016 BIO International Convention on Wednesday.

Former House Speaker Newt Gingrich addresses the Conservative Political Action Conference on March 8, 2014. (AP Photo/Cliff Owen)

Gingrich said Trump “made a really stupid mistake last week, and it took him about three days to learn.”

Gingrich’s remarks were in reference to a series of personal attacks Trump has directed toward U.S. District Judge Gonzalo Curiel, the judge hearing the Trump University lawsuit. Trump told the Wall Street Journal that Curiel has “an absolute conflict of interest” due to his Mexican heritage and Trump’s position that a wall should be built on the Mexican border.

Gingrich also condemned Trump’s attack on Curiel during an interview on "Fox News Sunday," calling it “one of the worst mistakes Trump has made.”

“I think it’s inexcusable,” Gingrich said, adding, “If a liberal were to attack Justice Clarence Thomas on the grounds that he’s black, we would all go crazy.”

Trump told Fox News' "Fox & Friends" on Monday that he was “surprised” by Gingrich’s critique.

“I thought was inappropriate what he said,” Trump said.

House Speaker Paul Ryan (R-Wis.) also condemned Trump’s attack on Curiel as the “textbook definition of a racist comment.”

Both Ryan and Gingrich have endorsed Trump.

Gingrich later called coverage of his comments "misleading."

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