FILE - In this March 16, 2016 file photo, Sen. Susan Collins, R-Maine, speaks with reporters on Capitol Hill in Washington. Collins is the latest Republican to reject GOP presidential candidate Donald Trump’s comments about the ethnic background of an American federal judge. Trump is insisting that U.S. District Judge Gonzalo Curiel, whose parents were born in Mexico, cannot be impartial overseeing the class action lawsuits against Trump University. Curiel’s ethnicity, Trump says, puts him in conflict with the presumptive GOP presidential nominee’s plan to build a wall with Mexico. (AP Photo/J. Scott Applewhite, File)

WASHINGTON - Republicans roundly scolded their own presidential candidate Monday, demanding Donald Trump apologize for — and just stop — talking about the ethnic background and impartiality of the American judge overseeing a lawsuit against Trump University.

Leading the roll call were two former rivals for the Republican presidential nomination.

Ohio Gov. John Kasich tweeted that Trump's offensive against the impartiality of U.S. District Judge Gonzalo Curiel "is flat-out wrong."

Trump, Kasich wrote, should "apologize to Judge Curiel & try to unite this country."

Chimed in Florida Sen. Marco Rubio, "It's wrong and I hope he stops."

Other prominent Republicans piled on, drawing a solid line between themselves and the billionaire candidate with whom they've developed a fragile peace. But that detente comes with caveats — chief of which is the understanding that Trump, nomination nearly in hand, will now focus on uniting the fractured GOP.

Trump, too, showed some deference for the truce, declining to immediately hit back at the Republican lawmakers who have demanded he change focus.

Rep. Chris Collins, R-N.Y., stuck up for Trump somewhat on CNN, insisting "Donald Trump is not a racist" but acknowledging "It's time to just let go of this ... and move on."

No mea culpa seemed forthcoming from the billionaire candidate. Trump insisted earlier Monday that his criticism of Curiel came in defence against relentless questions from reporters and others about lawsuits against Trump University. Trump said Curiel can't be impartial in the suits because the jurist's parents were born in Mexico and Trump wants to build a wall along the border. Last week, he denied on CNN that his remarks are racist.

"Public Service Announcement: Saying someone can't do a specific job because of his or her race is the literal definition of 'racism,'" tweeted Sen. Ben Sasse, R-Neb., a longtime Trump critic.

Curiel is a former federal prosecutor who was born in Indiana to parents who came from Mexico in the 1940s. He has not responded to Trump's attack, and Trump's legal team has not sought his removal from the case. Judges generally are thought to have conflicts of interest only in more specific situations, such as a financial interest in the outcome of the case.

Trump University is the target of two lawsuits — in San Diego and New York — which accuse the business of fleecing students with unfulfilled promises to teach them secrets of success in real estate. Trump has maintained that customers were overwhelmingly satisfied. Curiel is presiding over the suits in California.

"All I'm trying to do is figure out why I'm being treated so unfairly by a judge," Trump said Monday on Fox News Channel.

The Republican establishment responded in rare unison: Just stop.

"He needs to stop saying it. That man is an American — born in the United States," Rubio, son of Cuban immigrants, told Orlando television station WFTV. "I don't think it reflects well on the Republican Party. I don't think it reflects well on us as a nation."

Added Republican Sen. Susan Collins of Maine: "Donald Trump's comments on the ethnic heritage and religion of judges are absolutely unacceptable. His statement that Judge Curiel could not rule fairly because of his Mexican heritage does not represent our American values."

South Dakota Sen. John Thune, a member of the Senate GOP leadership, said: "Yeah, he's going to have to adapt. This is not working for him. They were inappropriate comments."

Ohio Sen. Rob Portman, who is in a competitive re-election race, emphasized that he's running "a very independent campaign" from Trump's.

"To suggest somebody is not capable of doing a job because of their ancestry is wrong and unacceptable," said Portman.

Said Texas Sen. John Cornyn, the Senate's No. 2 Republican, "I'm not going to be sucked into talking about Trump 24/7."

The cascade of condemnation began on the Sunday talk shows, when a trio of prominent Republicans firmly rejected Trump's focus on Curiel and urged him to make good on his promise to unite the fractured Republican Party. Senate Majority Leader Mitch McConnell said he "couldn't disagree more" with Trump's statements about Curiel's impartiality, adding that "we're all behind him now" — an implicit warning that such unity might not be the case for long. Senate Foreign Relations Committee Chairman Bob Corker said he doesn't condone Trump's statements about Curiel, then complained that his interview was supposed to be about foreign policy.

And former House speaker Newt Gingrich pointedly suggested that Trump start acting like "a potential leader of the United States."

Trump already has rejected calls for him to adjust his approach.

"I'm not changing," he said Tuesday at a fiery news conference at Trump Tower.

On Sunday, Trump doubled down on the idea. Asked on CBS whether a Muslim judge would be unfair given Trump's plan to ban Muslims from entering the U.S., Trump responded: "Yeah. That would be possible, absolutely."

That puts Trump in significant conflict with the Republicans he hopes to lead — including many of the ones who have opted to support him.

___

AP writer Alan Fram contributed to this report.

Follow Laurie Kellman on Twitter at http://www.twitter.com/APLaurieKellman

___

This story has been corrected to reflect that Curiel's parents came to the U.S. in the 1940s.

News from © The Associated Press, 2016