As Navy divers searched the Potomac River for bodies from the worst air crash in the United States in 20 years, President Trump zeroed in on what he saw as the cause: hiring programs that promote diversity.

The meaning behind his words was clear, that diversity equals incompetence. And for many historians, civil rights leaders, scholars and citizens, it was an unmistakable message of racism in plain sight at the highest levels of American government.

“His attacks on diversity, equity and inclusion aren’t about a particular program or some acronym — they’re just a sanitized substitute for the racist comments that can no longer be spoken openly,” Margaret Huang, the Southern Poverty Law Center’s president and chief executive, said during a call with civil rights leaders after Mr. Trump’s remarks. “But the message is the same, that women, ​Black and brown communities are inherently less capable, and if they hold positions of power or authority in government or business, it must be because the standards were lowered.​”

In the weeks since he took office, Mr. Trump has made a point of purging the federal government of D.E.I. initiatives in order to usher in what he called a “colorblind and merit-based” society. He even said his executive order eliminating the programs was “the most important federal civil rights measure in decades.”

In his actions, Mr. Trump has aligned himself with those who are brandishing the term D.E.I. as a catchall for discrimination against white people, and using it as a pejorative to attack nonwhite and female leaders as unqualified for their positions. After some of Mr. Trump’s allies in Congress disparagingly referred to Vice President Kamala Harris as a “D.E.I. hire” during the 2024 campaign, Mr. Trump refused to disavow the remarks.

The issue plays into deep tensions among Americans about the role of race in society and helped supercharge Mr. Trump’s political comeback. Many voters, conservative and not, hoped to see a correction to what they saw as progressive politics gone too far.

D.E.I., in effect, became an all-purpose target for society’s ills.

“It’s the latest term that serves as a proxy for race, and it’s used as a politically expedient slur, as a way to stoke white grievances and to give a convenient scapegoat to whatever ails our nation,” said Timothy Welbeck, the director of Temple University’s Center for Anti-Racism.

A Pew Research Center survey published in November found that the percentage of American workers who viewed D.E.I. programs negatively was on the rise, though a majority of workers still believed that it was a good thing for their employers to focus on.

A White House spokesman, Harrison Fields, said Democrats’ focus on D.E.I. undermined “decades of progress toward true equality.”

“The Trump administration rejects this backward thinking and will pursue an agenda that lifts everyone up with the chance to achieve the American dream,” he said in a statement.

In Mr. Trump’s remarks last week on the plane crash, he cited no evidence that diversity programs had anything to do with the fatal accident. When asked how he could say that diversity hiring was to blame, he said, “I have common sense.”

In a misleading claim, Mr. Trump insinuated that the administration of President Barack Obama — the first Black president — had stocked the Federal Aviation Administration with people who could not do their jobs.

“They actually came out with a directive: ‘too white,’” Mr. Trump said. His administration will be different, he went on. “We want the people that are competent.”

(Asked for details on the “too white” claim, the White House cited a lawsuit filed in 2015 by a conservative legal organization accusing the Obama administration of hiring practices that were “engineered to favor racial minorities.” That lawsuit is pending in court.)

The concept behind the federal government’s diversity programs is not new; it developed as a result of the Civil Rights Act of 1964. The goal is to remove discriminatory barriers for women, minority groups and people with disabilities from jobs. The earliest benefactors were white women, white people in rural areas and disabled veterans, Mr. Welbeck said.

The idea was that qualified people were being overlooked.

“It wasn’t discriminatory, because it was always about offering qualified people an opportunity to have a seat at the table,” Mr. Welbeck said. “They weren’t supplanting people, it was more so an opportunity for access.”

Critics of D.E.I. say an emphasis on diversity means that hiring standards are compromised and that the focus on race and gender is a distraction from more urgent goals and the overall mission. “When you don’t focus on safety and you focus on social justice or the environment, bad things happen,” Transportation Secretary Sean Duffy said on CNN on Sunday, speaking about the Washington plane crash.

The Trump administration, Mr. Duffy said, wants “the best and the brightest.”

But in the F.A.A. and elsewhere, officials say, the programs follow the same aptitude, medical and security standards for all hires.

Melik Abdul, a Republican strategist who was a part of the group Black Americans for Trump during the 2024 campaign, said the president’s stated commitment to merit was contradicted by some of his actions. He noted that Mr. Trump’s cabinet, which is predominantly white and male, is packed with loyalists.

“If it was all about merit, then we wouldn’t have Pete Hegseth,” said Mr. Abdul, referring to Mr. Trump’s defense secretary. Mr. Hegseth, a veteran and former Fox News host, took over the job of overseeing the Defense Department and its three million employees with little management experience beyond running veterans groups that he was accused of mismanaging.

“You can’t argue merit and say that is our most merit-based hire,” said Mr. Abdul, who has not broken with the president over the D.E.I. issue but says he is frustrated by Mr. Trump’s “obsession” with it.

For many, Mr. Trump’s attacks on D.E.I. point to his long history of inflaming racial tensions using dog whistles — from a campaign dating back to the 1980s against five Black men who were wrongfully convicted and ultimately exonerated of assaulting and raping a white woman, to his attempt to paint the first Black president as a noncitizen.

But now, they say, the dog whistle is a bullhorn.

The attacks on D.E.I. are part of a broad backlash against policies that Republicans denounce as left-wing politics run amok. One of Mr. Trump’s most aired ads about Ms. Harris during the presidential race ended with a tagline that took direct aim at transgender people: “Kamala is for they/them. President Trump is for you.”

Conservatives seized on what they describe as “woke” policies taking over American culture, particularly after the 2020 murder of George Floyd, 46-year-old Black man, by a Minneapolis police officer. The killing spurred schools, institutions and companies to adopt policies and training that sought to acknowledge and reverse systemic inequities.

In the process, they alienated some people.

“The oppressiveness of D.E.I. in the common culture, workplaces and in schools started to sink in,” said Dan Lennington, deputy counsel at the Wisconsin Institute for Law and Liberty, which has sought to wipe out diversity programs. “People being told they have white privilege and they ought to read a book about it is not the way to make friends and have influence.”

The uproar over D.E.I. is similar to the one over critical race theory a few years ago, in which conservative activists alleged that schools were indoctrinating students to become radical race warriors, and shaming students by teaching them about the history of slavery.

Critical race theory, a graduate-level concept that explores systemic racism in America, was rarely taught in K-12 schools. But some of its conceptual underpinnings, including that racism is embedded in societal systems like courts and schools, were a part of discussions on race more broadly.

The architect of the movement to turn critical race theory into a Republican rallying cry, Christopher F. Rufo, a senior fellow at the Manhattan Institute, laid out a blueprint for Mr. Trump in December to eliminate “left-wing radicalism” from the federal government.

In a post he called the “Counterrevolution Blueprint,” he wrote: “Trump can end these programs under his executive authority and replace D.E.I. with a policy of strict colorblind equality. This action would deliver an immediate shock to the bureaucracy.”

In an emailed response to an inquiry from The New York Times last week, Mr. Rufo said that he had been in touch with members of the Trump policy team since the summer of 2020, when the fight against critical race theory began. He said Mr. Trump’s D.E.I. fight had been years in the making by several conservative groups whose staff members have now joined the administration. He called the administration’s execution of their plans “phenomenal.”

“For an activist, there is no greater thrill than seeing a blueprint turn into reality,” he wrote. “It’s a new day in America.”

Civil rights groups say that it may be a new day, but that the themes have clear echoes, including the years after Reconstruction, which were marked by a violent backlash against Black people, and the tenure of President Woodrow Wilson, who resegregated the federal work force.

Samuel Spital, the associate director-counsel of the Legal Defense Fund, said Mr. Trump’s dismantling of D.E.I. was an attempt to “remake our society.”

It is an effort, he said, to “collectively gaslight the American people” about the real victims of discrimination in the United States.

Linda Qiu contributed reporting.