President Trump boards Marine One on Aug. 17. As Trump lobbed racially charged insults last week, most Republicans did not respond. (Jabin Botsford/The Washington Post)

The president of the United States had just lobbed another racially charged insult — this time calling his former top African American adviser a “dog” — but Sen. John Cornyn (R-Tex.) had no interest in talking about it.

“I’ve got more important things on my mind, so I really don’t have a comment on that,” said the Senate’s No. 2 Republican, chuckling at the question.

 Has President Trump ever said anything on race that made Cornyn uncomfortable? “I think the most important thing is to pay attention to what the president does, which I think has been good for the country,” the senator demurred.

What about his constituents back home — are they concerned? “I know you have to ask these questions but I’m not going to talk about that,” Cornyn said, politely ending the brief interview in the basement of the U.S. Capitol. “I just think that’s an endless little wild goose chase and I’m not going there.”

And so it went last week among Republicans: As Trump immersed the nation in a new wave of fraught battles over race, most GOP lawmakers tried to ignore the topic altogether. The studied avoidance is a reflection of the enduring reluctance of Republicans to confront Trump’s often divisive and inflammatory rhetoric, in part because the ­president remains deeply popular within a party dominated by older white voters.

The Washington Post reached out to all 51 Republican senators and six House Republican leaders asking them to participate in a brief interview about Trump and race. Only three senators agreed to participate: Jeff Flake of Arizona, David Perdue of Georgia and Tim Scott of South Carolina, the only black Republican in the Senate.

Flake, a frequent Trump critic who is retiring, rattled off examples when asked if there were times he felt Trump had been racially insensitive.

“It started long before his campaign, the whole Barack Obama, the birtherism . . . that was abhorrent, I thought,” Flake said in a phone interview. “And then you know, the Mexican rapists . . . on his first official day as a campaign. And then you know, Judge Curiel, the statement that he couldn’t judge because of his heritage. Failure to, you know, condemn in Charlottesville. Just the willingness to go there, all the time. Muslim ban. This kind of divide-and-conquer strategy. It’s just — it’s been one thing after another.”

Six other lawmakers granted impromptu interviews when approached in the Capitol, although most declined to be specific about whether they were uncomfortable with any of Trump’s statements on race. One exception was Sen. Bob Corker of Tennessee, another Trump critic who is leaving Congress in January.

 “It’s a formula that I think they think works for them, as it relates to winning,” Corker said, referring to the use of divisive racial issues by Trump and his advisers. “I think that’s their kind of governing. I think that’s how they think they stay in power, is to divide.”

Several other lawmakers said they did not like some of Trump’s language, especially on race, but did not consider Trump to be racist.

Sen. John Thune (R-S.D.), the No. 3 Republican in the Senate, said Trump’s description of former black adviser Omarosa Manigault Newman as a “dog” was “not appropriate, ever.” But he stopped short of pointing to a time when he felt the president had crossed a racial boundary. 

“I just think that’s the way he reacts and the way he interacts with people who attack him,” Thune said. “I don’t condone it. But I think it’s probably part built into his — it’s just going to be in his DNA.”

The month of August — which included the first anniversary of the deadly white supremacist rally in Charlottesville — has seen Trump unleash a steady tide of racially charged invective, including questioning the intelligence of basketball star LeBron James, attacking Chinese college students and reviving his attacks on anthem protests by black NFL players. At one point last week, White House press secretary Sarah Huckabee Sanders said she could not guarantee that no audio recording exists of Trump using the n-word, as Manigault Newman alleges in her book.

Republicans have struggled over issues of race since the Civil Rights era, with periodic efforts to appeal to blacks, Latinos and other minorities. Trump’s critics within the party fear that, in an increasingly diverse nation, the president is reopening wounds many Republicans had sought to heal.

Trump and his allies frequently counter by offering economic data that they say is favorable to minorities, seeking to separate Trump’s harsh rhetoric from his policy agenda.

But some longtime party stalwarts worry about the long-term consequences of the party’s near-silence on race.

Mike Murphy, a veteran Republican consultant and vocal Trump critic, bemoaned “the larger moral cowardice that has overtaken the party.”

“Trump’s shtick is that he’s the grievance candidate,” Murphy said. “He’s focused on the economically squeezed Caucasian voter. . . . He is speaking to that rage. Mexican rapists, clever Chinese traders, African American people as dogs. That’s Trump’s DNA.”

Some Republican lawmakers who have publicly criticized Trump on the issue of race, particularly in the immediate aftermath of Charlottesville, believe their best course of action has been to articulate their own views.

“I’m glad that I stood out, was clear and sometimes critical of comments that are inconsistent with the American ethos on the issue of race, the evolution that we’ve gone through as a nation,” Scott said in an interview. “I think I will look back with some pride that I was able to see the forest for the trees.”

Beginning with the violent opposition among some white voters to the Civil Rights Act of 1964, Republican leaders began appealing to white voters — especially in the South — with calls for “law and order” and vows to defend states’ rights as the federal government enforced the new laws.

Richard Nixon’s “Southern strategy” during the 1968 presidential campaign worked to bring longtime Southern Democrats into the Republican fold by courting those dismayed by the civil rights policies pushed by Democratic President Lyndon B. Johnson. Four years later, Nixon further consolidated that bloc in his sweeping reelection victory, in part by picking up voters who had previously backed the White House bid of Democrat and segregationist George Wallace, who was shot and effectively sidelined during the 1972 campaign.

During the 1980 campaign, Ronald Reagan was criticized for speaking about states’ rights near Philadelphia, Miss., the town where three civil rights workers were murdered in 1964. And George H.W. Bush was rebuked by critics in 1988 for airing a television ad that showed the image of a convicted black murderer, Willie Horton, in arguing that his Democratic rival was soft on crime.

 Alvin S. Felzenberg, a conservative historian who has written extensively on the American right, said Republicans are haunted by this past but also seemingly unable to escape it.

“The Republican Party since the late 1960s has had a particular problem with race and they don’t want to admit it,” Felzenberg said. “They don’t want to admit it once again with Trump because they don’t want to offend their own voters. You can hear the chattering teeth in primaries.”

The presidency of George W. Bush ushered in a period when the national Republican Party sought to grow its support among blacks and Hispanics. As the Republican National Committee chairman in 2005, Ken Mehlman — who managed Bush’s reelection campaign — publicly apologized for Nixon’s “Southern strategy,” calling it “wrong.”

And following Mitt Romney’s loss in 2012 to President Barack Obama, the party produced an autopsy report arguing that the party would need to make inroads among minority voters to survive changing demographics.

Trump has largely upended all of that, however, riding to electoral victory by focusing almost exclusively on disaffected white voters, including wooing previously Democratic union voters in the Midwest and Northeast. 

Dianne Pinderhughes, a professor at the University of Notre Dame who focuses on race and politics, said the president’s handling of race is also part of a recurring historical trend: Republicans subtly and not-so-subtly reassure white Americans that their status in the country remains intact amid a fast-changing culture.

“He’s trying to convince white people that the way to keep their long-term status is to keep out people of color, keep out immigrants, and keep blacks down, and they’ll feel better off by doing so,” Pinderhughes said. “In turn, some white people are excited and responsive. It’s not all whites, but it’s significant enough to be recognized by other Republicans, who decide to stay quiet about it.”

There is evidence that Trump’s strategy is working — or at least breaking down along predictable partisan lines. 

 In a January Washington Post-ABC News poll conducted immediately after Trump called African nations “s---hole” countries, 52 percent of Americans said Trump is biased against black people. But among Republicans, 16 percent said Trump is biased against blacks while 79 percent said he was not. Meanwhile, 82 percent of Democrats and 54 percent of independents said Trump is biased, as did 79 percent of African Americans.

Jonathan V. Last, digital editor at the Weekly Standard, seemed to capture the quiet resignation facing many Republicans as he imagined, in a tweet, the party’s hypothetical response to actual audio surfacing of Trump saying the n-word. “You can’t prove it’s him saying it,” he wrote, before continuing: “So he said it; old news. Thank God he said it; about time someone did. The real racists are the people complaining.”

“In fairness to the Republicans, though, my general view is that Trump is a symptom and not a cause,” Last added, in response to an emailed question about his tweet. “And Trump may have simply revealed the extent to which all of our politics has devolved into grotesque, sub-ideological tribalism.”

The president’s defenders say that he is not racist nor is he exploiting the country’s existing racial divisions. Rudolph W. Giuliani, the president’s lead lawyer for special counsel Robert S. Mueller III’s ongoing Russia probe, noted several prominent African Americans with whom the president gets along.

“If the presidents likes you, he likes you — white, black, whatever,” Giuliani said. “He’s not a fan of Omarosa, but he’s become a fan of Kanye West. He likes Tiger Woods, but he doesn’t like LeBron James.” 

Some of those who find themselves torn — supporting much of Trump’s policy agenda while feeling queasy about some of his language — say they don’t believe he is racist and think Democrats are overplaying their hand.

Ari Fleischer, who served as press secretary under George W. Bush and was an author of the autopsy report, said he believes that while Trump is squandering opportunities to win over minority voters, there exists a “line between being a boor and being a racist.” 

“While I find his approach endlessly frustrating, I find his critics even more out to lunch and over the top,” Fleischer said, noting that Democrats have lobbed accusations of racism against previous Republican presidential nominees, including Romney and Sen. John McCain (R-Ariz.). “They do it to everybody, and they’ll do it to whoever runs after Trump, too. To me, the Democrats have no credibility on this issue.”

Perdue said in an interview that he believes Trump is results-focused and “trying to be ­all-inclusive,” and that Democrats are the ones using race as a political issue.

“Well, I hope they will,” Perdue said. “I have many friends in the African American community and they’re tired of being treated as pawns.” 

But Republicans who believe that Trump has galloped past norms of civil society on race and other issues worry about the costs the party may ultimately pay, both politically and morally.

Stuart Stevens, a Mississippi-born Republican operative who served as a senior strategist on Romney’s 2012 presidential campaign, said the issue of race is definitional.

“Look, George Wallace did a lot of good things,” Stevens said. “He got free school textbooks. He increased access to build roads. But I don’t think history remembers those George Wallace people as the free-textbook-George-Wallace people.”

“Everybody,” he concluded, “has got to come to their own answer about that.”  

Scott Clement, Mike DeBonis and Sean Sullivan contributed to this report.