If only we could send them back.

Republican lawmakers have long cut profiles in cowardice during the Trump presidency, but never before have the consequences of their leadership vacuum been as vivid.

GOP legislators professed dismay when a crowd at President Trump's North Carolina rally, riled by his attacks on a member of Congress who emigrated from Africa as a child, broke into a racist chant of "Send her back!"

"Not acceptable," proclaimed Rep. Tom Emmer of Minnesota, head of the National Republican Congressional Committee.

"That's offensive," judged Rep. Mark Walker of North Carolina, the House GOP conference vice chairman.

House Minority Leader Kevin McCarthy, R-Calif., likewise declared there is "no place in our party and no place in this country" for such words.

Yet when Trump himself said a few days earlier that four nonwhite members of Congress, including three born in the United States, should "go back" to the countries they came from, Republican lawmakers responded with near-complete silence. When the House, 48 hours before the chanting in North Carolina, took up a resolution condemning these "racist comments that have legitimized and increased fear and hatred of new Americans and people of color," only four of 197 House Republicans joined the denunciation.

But they're appalled when thousands of people in an arena chant sentiments much like the ones they tacitly bless when Trump says them? Even after the grotesque display at the rally (Trump, who later distanced himself from the chant, could be seen savoring it at the time), Senate GOP leader Mitch McConnell said that "the president is onto something."

The lawmakers' behavior is in a way worse than Trump's. He has long demonstrated that he has no sense of propriety -- only an instinct for the expedient. We can expect no more of him. The real injury comes when elected officials who know better nod and wink at Trump's behavior, thereby signaling to the public that it's acceptable.

Some Republicans have belatedly found their voices this time, likely because they sense political damage. A USA Today/Ipsos poll this week found that 65% of Americans believe it's racist to tell minority Americans to "go back to where they came from." Even 45% of Republicans believe this. These ordinary Americans -- including many Trump supporters -- take a stronger moral position than their so-called leaders.

What's more, 72% of Americans, including 68% of Republicans, believe it's patriotic to point out where America falls short -- the offense for which Trump attacked the nonwhite lawmakers.

Leaders shape public opinion. That's why Republican voters' views of immigration and free trade have soured during Trump's tenure. Republican members of Congress, if they chose to lead, could counter his excesses. Instead, for fear of losing their jobs, they cower -- and their silence normalizes the obscene.

Only after they're out do they manage to find their voices. Rep. Justin Amash of Michigan, who just quit the GOP, correctly judged that the "send her back" chant "is the inevitable consequence of President Trump's demagoguery. This is how history's worst episodes begin."

Former Trump adviser Anthony Scaramucci, likewise, had his invitation to address the Palm Beach County GOP yanked after he criticized Trump's words. He warned that Trump is "turning into" a racist.

And then there's Paul Ryan, who, during his troubled speakership, maintained a pro-Trump posture, rarely breaking with him publicly. Now out of power, Ryan told Politico's Tim Alberta for his new book, "American Carnage," that Trump "didn't know anything about government."

Belatedly, Ryan laments the injuries to institutions and moral standards. "We've gotten so numbed by it all," said the man who for two years served as chief anesthetist.

All but a handful of the 250 Republicans in Congress are sensible enough to know that the now-former British ambassador, Kim Darroch, had it right when he predicted, in a leaked document, that Trump's administration won't "become substantially more normal; less dysfunctional; less unpredictable; less faction riven; less diplomatically clumsy and inept."

Yet the Republicans remain silent. And Trump pronounces himself once again to be a "stable genius." And threatens to defy a Supreme Court ruling before reversing himself. And bids farewell to his ninth Cabinet officer -- a modern record -- in yet another scandal. And sends mixed messages to Iran, North Korea and Turkey. And hosts conspiracy theorists at the White House. And now launches a racist attack on dark-skinned members of Congress.

So it will continue. Republican lawmakers made their choice to give Trump their tacit approval. The ugliness in North Carolina is what happens when leaders become mere followers.

Dana Milbank (@Milbank) writes for The Washington Post.