The Republican Party, which put up with Donald Trump’s racist, crackpot ravings throughout the primary campaign, is finally showing signs of resistance. Even those who have endorsed Trump, like Newt Gingrich, are now disassociating themselves from Trump’s line that Judge Gonzalo Curiel cannot be expected to be an impartial arbiter of the case against Trump University simply because of his Mexican ancestry. Paul Ryan, who officially endorsed Trump only days ago, said Trump’s remarks are “indefensible” and a “textbook case” of racism. Mitch McConnell urged Trump to drop the attacks against “various minority groups in the country” and “get on message.”

The question is: What took them so long? After all, the attack on Curiel is just the latest in an endless stream of racist comments Trump has made throughout his career, ranging from his calls to execute the Central Park Five (who were later exonerated), to his questioning of President Obama’s citizenship, to his references to Mexican “rapists,” to his promise to bar Muslims from entering the United States.

What makes the Curiel case so special that Republicans are acting as if Trump has finally crossed the line? The most likely explanation is that Curiel is a member of the governing elite, like Gingrich and Ryan, and in his capacity as a judge is part of the supposedly apolitical ruling class. Joseph McCarthy followed a similar trajectory: He destroyed the lives of countless Americans with his demagogic anti-communism, but only received bipartisan pushback when he went after the Army in 1954.

As Talking Points Memo editor Josh Marshall shrewdly noted on Twitter, Curiel is a specific individual with a biography, whereas the objects of Trump’s other attacks were mainly hypotheticals. Trump was promising to bar Muslims and deport undocumented immigrants, but the very fact that these measures would encompass millions of faceless people makes them hard to think about except in abstract terms.

By contrast, the smearing of Curiel took place in the here and now, against someone with a name, a face, and a particular history. Gonzalo Curiel was born in Indiana in 1953. His ascent to a judgeship via law school and hard work is a fulfillment of the American dream, a story of playing by the rules and rising up the social ladder. To launch a racist attack against someone like Curiel, as Trump did, was to deny national values that both Republicans and Democrats share. This wasn’t the type of structural racism that conservatives often deny exists. It was a very visible example of racism personally aimed at a successful member of American society, hence a rejection of the type of society conservatives claim they want.

When Trump denigrated John McCain’s war record or suggested Jeb Bush was a “low energy” loser, that could be dismissed as rough-and-tumble politics, albeit with unusually sharp elbows. But criticizing the ethnicity of a judge violates fundamental norms of anti-racism. When you factor in the possibility that Trump could be president, it also becomes a separation-of-powers issue.

This is particularly relevant as we transition to the general election phase of the 2016 cycle. Trump had made similar remarks against Judge Curiel in February, but they only caused a small ripple that was swept away by the larger tide of Trumpian absurdity. Now everything Trump says not only gets more sustained attention, but is also viewed through a different lens. People outside the GOP base are starting to think seriously about what sort of president Trump would be, and it’s scaring them.