At a campaign rally in San Diego on Friday, Donald Trump spent 12 minutes attacking the federal judge who is presiding over a lawsuit against his Trump University, at one point noting out of the blue that he believes the judge, Gonzalo P. Curiel, is “Mexican.” (Curiel was born in Indiana. His parents were immigrants from Mexico.)

CNN’s Jim Acosta pointedly asked Trump at a press conference today, “Why mention that the judge is Mexican?”

Trump replied, “Because I’m a man of principle,” before continuing with his defense of Trump University, his failed real estate seminar company.

While Trump’s vitriolic statements about a sitting federal judge comprise yet another unfortunate and unprecedented aspect of his presidential campaign, his attack on Curiel’s heritage is even more alarming.

As the presumptive Republican nominee, Trump is now implying that a judge’s ethnicity and the birthplace of his parents are reasons enough to believe that his rulings from the bench are suspect.

Trump’s comments should not be brushed aside as yet another in a long string of outrageous attacks against those whom he perceives have slighted him. They are whole-cloth attacks against a group who comprise approximately 10 percent of the United State’s population.

More than 35 million Americans count themselves as having Mexican heritage, according to the Census Bureau. In Donald Trump’s America, would this become a reason to be treated as untrustworthy or even to be rejected from important government jobs?

Trump began his primary campaign by claiming that Mexican immigrants are “bringing drugs. They’re bringing crime. They’re rapists.” Now he enters the general election by invoking a judge’s Mexican heritage for the purpose of turning it into a slur. (Previously, he criticized the judge as “Spanish.”)

Even if the Republican nominee was simply bashing a judge whose decisions he found unfair, Trump continues to foster a dangerous climate, signaling to racists that their bigotry is a part of his formula for “making America great again.”

After John Kasich and Ted Cruz dropped out of the presidential race, Trump was supposed to begin moderating his tone and message. His campaign was no longer going to focus on the overwhelmingly white Republican electorate, but begin to reach out to all Americans.

Reports of Trump’s pivot to the center were greatly exaggerated, as he has instead continued to take the same hostile, belligerent, and occasionally offensive tone toward whole groups of Americans that he views as opposing his campaign.

His answer to Acosta at today’s press conference was accurate. Donald Trump is a man guided by his principles — among them bigotry, which he once again was proud to display.