There is a difference between an unconventional campaign and one that crosses the line of what is acceptable and must be called out in the most unequivocal terms.

Donald Trump has crossed that line before, but never so definitively as when he said the presiding judge in the Trump University lawsuit could not render a fair decision on the case because he’s Mexican.

U.S. District Judge Gonzalo Curiel was born in Indiana to Mexican parents, making him Mexican-American. That, apparently, is enough to disqualify him in the eyes of the man who wants to be president. It is a despicable, baseless conclusion that Trump made worse by later adding that he didn’t think a Muslim judge could deliver an impartial decision on his case either.

Republicans can proceed as they choose, but they should know that no rhetorical parsing will adequately separate them from the man they are about to choose as their party’s standard-bearer. Senate Majority Leader Mitch McConnell condemned Trump’s remarks, but just to make sure no one thought he’d completely broken with him, McConnell said, “We’re all behind him now. … I hope he’ll change his direction.”

Indeed. Except there is no reason to think he will. Trump’s boorish, strongman act is what has gotten him this far. Tapping into a vein of fear and frustration among voters, Trump wiped out the GOP field one by one and got most of them to kiss his ring when all was done. Party leaders who initially cried “Never Trump” have knuckled under, including House Speaker Paul Ryan, whose prolonged standoff against Trump got him exactly nothing. The more Trump thumbs his nose at conventional Republicans, the more his acolytes are convinced that he will lay waste to the status quo once elected.

There is no evidence that Trump will pivot and begin a more constructive, issues-based campaign. And to make it perfectly clear, he declared in response to his Curiel insult: “I will not change.”

This has been an unconventional year. But before they align themselves with Trump’s overtly racist and divisive views, Republicans should recognize the damage he’s inflicting on the party — the kind of damage that could last for years to come.