In Hollywood, Harriet Tubman is played in a new movie by a black British woman, much to the annoyance of some black Americans. On the United States census, an ultrawealthy Nigerian immigrant and a struggling African-American woman from the South are expected to check the same box. When many American universities tout their diversity numbers, black students who were born in the Bronx and the Bahamas are counted as the same.

A spirited debate is playing out in black communities across America over the degree to which identity ought to be defined by African heritage — or whether ancestral links to slavery are what should count most of all.

Tensions between black Americans who descended from slavery and black immigrants from Africa and the Caribbean are not new, but a group of online agitators is trying to turn those disagreements into a political movement.

They want colleges, employers and the federal government to prioritize black Americans whose ancestors toiled in bondage, and they argue that affirmative action policies originally designed to help the descendants of slavery in America have largely been used to benefit other groups, including immigrants from Africa and the Caribbean.

The American descendants of slavery, they say, should have their own racial category on census forms and college applications, and not be lumped in with others with similar skin color but vastly different lived experiences.

The group, which calls itself ADOS, for the American Descendants of Slavery, is small in number, with active supporters estimated to be in the thousands. But the discussion they are provoking is coursing through conversations far and wide.

Those who embrace its philosophy point to disparities between black people who immigrated to the United States voluntarily, and others whose ancestors were brought in chains.

Roughly 10 percent of the 40 million black people living in the United States were born abroad, according to the Pew Research Center, up from 3 percent in 1980. African immigrants are more likely to have college degrees than blacks and whites who were born in the United States.

A 2007 study published in the American Journal of Education found that 41 percent of black freshmen at Ivy League colleges were immigrants or the children of immigrants, even though those groups represent 13 percent of the black population in the United States.

In 2017, black students at Cornell University protested for the admission of more “underrepresented black students,” who they defined as black Americans with several generations in the United States. “There is a lack of investment in black students whose families were affected directly by the African Holocaust in America,” the students wrote to the president of the university.

University administrators say that black students from other countries contribute to increased diversity on campus, even if their admittance does not mitigate the injustices of American slavery. Many black immigrant groups are also descended from slavery in other countries.

The film producer Tariq Nasheed is among the outspoken defenders of the idea that the American descendants of slavery should have their own ethnic identity.

“Every other group when they get here goes out of their way to say, ‘I’m Jamaican. I’m Nigerian. I’m from Somalia,’” he said. “But when we decide to say, ‘O.K. We are a distinct ethnic group,’ people look at that as negative.”

This year, responding to requests for “more detailed, disaggregated data for our diverse American experience,” the Census Bureau announced that African-Americans will be able to list their origins on census forms for the first time, instead of simply checking “Black.”

The goal of ADOS’s two founders — Antonio Moore, a Los Angeles defense attorney, and Yvette Carnell, a former aide to Democrat lawmakers in Washington — is to harness frustrations among black Americans by seizing on the nation’s shifting demographics.

Embracing their role as insurgents, Mr. Moore and Ms. Carnell held their first national conference in October, and have made reparations for the brutal system of slavery upon which the United States was built a key tenet of their platform.

Their movement has also become a lightning rod for criticism on the left. Its skepticism of immigration sometimes strikes a tone similar to that of President Trump. And the group has fiercely attacked the Democratic Party, urging black voters to abstain from voting for the next Democratic presidential nominee unless he or she produces a specific economic plan for the nation’s ADOS population.

Such tactics have led some to accuse the group of sowing division among African-Americans and engaging in a form of voter suppression not unlike the voter purges and gerrymandering efforts pushed by some Republicans.

“Not voting will result in another term of Donald Trump,” said Brandon Gassaway, national press secretary of the Democratic National Committee.

Shireen Mitchell, the founder of Stop Online Violence Against Women, has been embroiled in an online battle with ADOS activists for months. Ms. Mitchell contends that the group’s leaders are “using reparations as a weapon” to make Mr. Trump more palatable to black voters. Others have pointed out that Ms. Carnell once appeared on her YouTube channel in a “Make America Great Again” hat.

Credit…Danielle Scruggs for The New York Times
Credit…Danielle Scruggs for The New York Times
Credit…Danielle Scruggs for The New York Times
Credit…Danielle Scruggs for The New York Times

Over a thousand people attended the group’s first national conference, hosted by Simmons College of Kentucky. Guest speakers included Marianne Williamson, a white self-help author who has made reparations a key plank of her platform as a minor Democratic presidential candidate, as well as Cornel West, a black Harvard professor who said ADOS is giving a voice to working-class black people.

Tara Perry, a 35-year-old paralegal, was among the attendees. A former employee of the Los Angeles Black Worker Center, which used to count the number of black laborers at construction sites, Ms. Perry said she believed that the influx of Mexican immigrants had made it more difficult for black men to find construction jobs in the city.

“People call us divisive. We’re not divisive. We’re self-interested,” said Ms. Perry, adding that she was prepared to see Mr. Trump re-elected.

Critics consider the movement a Trojan horse meant to infiltrate the black community with a right-wing agenda, and question why the group would target Democrats, who have been far more open to discussions of reparations.

“You are willing to let Donald Trump win, who clearly says he doesn’t see reparations happening?” asked Talib Kweli Greene, a rapper and activist who has become a vocal opponent of the group. “Get out of here!”

Recently, Hollywood has become the source of much of the frustration around the dividing line between United States-born African-Americans and black immigrants. When the black British actress Cynthia Erivo was hired to play the abolitionist Harriet Tubman, the casting received immediate backlash. Similarly, the filmmaker Jordan Peele has been criticized for hiring Lupita Nyong’o, who is Kenyan, and Daniel Kaluuya, who is British, to play African-American characters in his movies.

But Mr. Moore, 39, and Ms. Carnell, 44, say they are not scapegoating black immigrants or trying to lead black voters astray. They say they are merely demanding something tangible from Democrats in exchange for votes and trying to raise awareness around the economic struggles of many black Americans.

Ms. Carnell said she learned of the huge disparities in inherited wealth that left black Americans with a tiny share of the economic pie by reading reports, including an Institute for Policy Studies report that predicted the median wealth of black families would drop to zero by 2053. Mr. Moore had been talking about some of the same studies on his own YouTube channel. The two joined forces in 2016 and coined the term ADOS, which spread as a hashtag on social media.


Credit…Danielle Scruggs for The New York Times

“What they have done is taken the racial wealth divide field out of academia and packaged it under a populist hashtag,” said Dedrick Asante-Muhammad, of the Institute for Policy Studies.

Mr. Asante-Muhammad lamented that the rhetoric of the movement comes off as anti-immigrant and said that Mr. Moore and Ms. Carnell “over-dramatize” the impact of African immigrants on the wealth and opportunities available to black Americans.

William Darity Jr., a professor at Duke University, has written a series of reports about wealth inequality cited by Mr. Moore and Ms. Carnell. In one report, Dr. Darity found that the median net worth of white households in Los Angeles was $355,000, compared with $4,000 for black Americans. African immigrants in the city had a median net worth of $72,000. Dr. Darity’s research also shows that not all immigrant groups are wealthy.

Dr. Darity did not attend the recent conference in Kentucky, but he said he saw ADOS as a social justice movement on behalf of a segment of the black population that is being left behind.

But not everyone agrees with Dr. Darity’s view that empowering disadvantaged African-Americans is the extent of the group’s message. Some who have used the hashtag have used racist, violent language when going after their detractors. Ms. Carnell once defended the term “blood and soil,” a Nazi slogan, on Twitter.

Ms. Mitchell, the founder of Stop Online Violence Against Women, said she was harassed online by the group’s supporters after she mentioned ADOS on Joy Reid’s MSNBC show in a segment about Russian disinformation campaigns.

During the segment, Ms. Mitchell implied that ADOS was made up of Russian bots impersonating real black people online. After the segment aired, the group’s supporters harassed Ms. Mitchell as well as Ms. Reid, who they noted was born to immigrants.

“If you do not agree with them, or acknowledge their existence, they go after you,” Ms. Mitchell said.

Ms. Carnell has also been criticized for her past service on the board of Progressives for Immigration Reform, an anti-immigration group that has received funding from a foundation linked to John Tanton, who was referred to as “the puppeteer” of the nation’s nativist movement by the Southern Poverty Law Center.

A September newsletter from Progressives for Immigration Reform touted the growing political clout of ADOS and praised it as “a movement that understands the impact unbridled immigration has had on our country’s most vulnerable workers.”

This summer, ADOS ignited a flurry of criticism after Ms. Carnell complained that Senator Kamala Harris, Democrat of California, was running for president as an African-American candidate but had failed to put forth an agenda for black people. She noted that Ms. Harris is the daughter of an Indian mother and a Jamaican father. Critics quickly accused Ms. Carnell of “birtherism” and xenophobia.

And although Ms. Carnell and Mr. Moore say ADOS is a nonpartisan movement, the hashtag has been used by conservatives who support Mr. Trump.

“I like #ADOS,” Ann Coulter, a white conservative commentator, wrote on Twitter. “But I think it should be #DOAS — Descendants of American slaves. Not Haitian slaves, not Moroccan slaves.”

At the conference in Kentucky, supporters pushed back against the idea that they were anti-immigrant or surrogates of the president’s agenda.

“We’re not xenophobes,” said Mark Stevenson, a director of talent acquisition in the Navy who said he founded an ADOS chapter in Columbus, Ohio, this summer. “If you ask somebody who is Latino what is their heritage, they’ll tell you they are Puerto Rican or Dominican or Cuban.”

“This is our heritage,” he added. “I don’t see the issue.”