(CNN) Donald Trump on Monday ordered surrogates on a campaign call to keep criticizing a federal judge overseeing a lawsuit against him, according to two sources on the call.

Trump has ignited a firestorm by calling federal Judge Gonzalo Curiel a "hater" and describing the Indiana-born jurist as "a Mexican."

The presumptive Republican nominee told top surrogates on the conference call to ignore a campaign memo issued the night before urging them to dodge questions about the lawsuit and Trump's controversial questioning of the judge's impartiality, the sources told CNN. The call was first reported by Bloomberg Politics

Trump made it clear on the conference call that there would be no apologies for his comments about the judge and said he feels that he's been wronged in the fierce criticism he has faced over the comments, a top Republican official and a Trump campaign surrogate told CNN, requesting anonymity to divulge details of a private conversation.

"He believes in his case and I don't think he's going to back down on Judge Curiel," a third source on the call told CNN.

Instead, Trump readied his team for a longer fight about the issue, urging surrogates to back him up and go after the media for pressing the line that his comments about the judge were racist.

The news comes after prominent Republicans, including former House Speaker Newt Gingrich, a Trump backer, came out strongly against Trump's comments about the judge. Gingrich called them "one of the worst mistakes Trump has made."

The Republican official on the call told CNN that the campaign was dismayed and felt let down by Gingrich's criticism.

Trump and a top campaign official on the call also pressed surrogates to raise the issue of judicial activism as a larger problem, the Republican source said, with Trump specifically pointing to Judge Gonzalo Curiel's membership with the La Raza Lawyers of California, a Latino bar association, according to Bloomberg.

The surrogates on the call included former Arizona Gov. Jan Brewer, former Massachusetts Sen. Scott Brown and Florida Attorney General Pam Bondi, Bloomberg reported.

Trump campaign spokeswoman Hope Hicks declined to address the campaign's messaging on Trump University and Curiel, describing the call in a statement as a thank you call.

"It was a very positive call to discuss overall messaging and, more importantly, to thank surrogates for their incredible support throughout the primaries as they come to an end," she said.

Armstrong Williams, a confidant of Trump surrogate Ben Carson, told CNN Monday the retired neurosurgeon was on the call but disputed the accounts that Trump was doubling down on his criticism of Curiel.

"Dr. Carson says they must have been on a different phone call," Williams said. "Mr. Trump took the time to explain what he was trying to explain and made it clear that they should respect judges, that it was not about race and ethnicity, but that it was about judicial activism."

Williams also said he has never received campaign talking points.

Trump's order for surrogates to back him up on his critiques of Curiel came only after Trump learned during the conference call that his campaign staff had ordered surrogates not to do so.

Brewer, one of Trump's earliest public supporters, interrupted Trump's call for supporters to press his line of attack on the matter and informed him she had received a memo of talking points a day earlier that ordered surrogates to stray from the topic, according to Bloomberg's reporting.

"Take that order and throw it the hell out," Trump said, according to Bloomberg, which is based on the account of two supporters on the conference call.

The memo told surrogates "they're not authorized to discuss matters concerning the Trump Organization including corporate news such as the Trump University case," according to a copy of the email obtained by Bloomberg, which also told surrogates to say that "the case will be tried in the courtroom in front of a jury -- not in the media."