She did not "go quietly," said the official, who spoke on the condition of anonymity to discuss a personnel matter. Although her resignation is effective Jan. 20, the Secret Service said it had deactivated her security badge granting access to the White House grounds. The agency said it was not involved in escorting her off the property.
Her rivals cast the move as an overdue housecleaning, but her departure, on the day that black voters helped catapult Democrat Doug Jones to an upset victory in the Senate race in Alabama, highlighted perhaps a more worrisome issue for the White House and the Republican Party heading into a midterm election year — the stark lack of diversity in Trump's administration and the GOP's diminishing appeal to minority communities.
Manigault, who earned the top-level staff annual salary of $179,700, was, along with Housing and Urban Development Secretary Ben Carson, one of two black officials among Trump's more than three dozen Cabinet members and senior staffers.
Her presence hardly immunized Trump — who sparked outrage with his handling of the white supremacist rally in Charlottesville and NFL players' national anthem protests — from criticism over his stance on race and diversity. Acting in an ill- defined capacity, Manigault struggled to make a connection with African American constituencies to support Trump's agenda and chafed at criticism that she had sold out her integrity for a White House job.
Departures that made headlines during Trump’s administration
Michael Steele, a former Republican National Committee chairman, pointed to Trump's endorsement of Republican candidate Roy Moore in the U.S. Senate race in Alabama despite Moore's history of racially insensitive remarks and the allegations against him of sexual improprieties with teenage girls.
Ninety-six percent of Alabama black voters supported Jones.
"It was a resounding rejection of our party among African Americans who see it as racially charged and not within their interests," Steele said. "All that occurred during Omarosa's tenure and relationship with the president. Either she did not have the cachet to move the president or she is complicit in it. I don't know which it is."
In the end, Manigault's bond with Trump appeared to be one of kindred spirits instead of policy adviser. It was a union forged during their appearance on the first season of "The Apprentice" in 2004, where she gained fame playing the role of a backbiting villain who would kneecap other contestants in her quest to win. She did not take the top prize, but she became a favorite of Trump, who invited her to participate in subsequent iterations of the show.
"Thank you Omarosa for your service! I wish you continued success," Trump tweeted late Wednesday.
She brought that confrontational persona to the political arena, fiercely defending Trump against accusations that he was racist and sexist. She and Carson often joined Trump at events with African American groups, and she was present Saturday as the president spoke before the public opening of a civil rights museum in Mississippi.
Friends said that despite her relationship with Trump, Manigault did not agree with his handling of some issues involving race, such as last summer's rally by white nationalists and white supremacists in Charlottesville in which a counterprotester was killed.
The president was slow to condemn the hate groups and suggested that "both sides" were at fault for the violence.
"As recently as last week she told me about her concerns about the president endorsing Roy Moore. It bothered her, being a woman," said Armstrong Williams, a businessman and a longtime friend. He did not know whether she raised her objections with the president.
In a brief statement, White House press secretary Sarah Huckabee Sanders said Manigault had resigned "to pursue other opportunities. . . . We wish her the best in future endeavors and are grateful for her service."
Longtime black Republicans chafed at Manigault's White House post, arguing that she was not a true member of the party. Before Trump entered the presidential race, she had backed Democrat Hillary Clinton. Manigault also worked briefly as a low-level aide in the White House during President Bill Clinton's tenure.
She was asked to leave that job, a former official said, because she was "so disruptive."
Manigault was a polarizing figure inside the Trump White House, known for interrupting meetings, subverting chains of command and erupting on other aides she disliked. And in recent months, whatever outsize cachet she once enjoyed had waned considerably as her job duties grew increasingly ill-defined, according to White House officials.
In recent months, Manigault engaged in public spats with African American groups, including the Congressional Black Caucus, grass-roots activists and black journalists.
She also was criticized for promising that Trump would provide additional funding to struggling historically black colleges and universities — help that did not materialize. The presidents of those institutions gained little other than a highly publicized meeting with administration officials in February, which included a photo op with Trump in the Oval Office.
Jamil Smith, a contributing opinion columnist for the Los Angeles Times who writes frequently about race, said Manigault had lost any significant standing within the black community.
"She has long ago been disinvited from the cookout, so to speak," Smith said. Her shortcomings were "not necessarily because of any lack of black authenticity on her part. She was just completely unqualified and inexperienced. That matters."
Leah Wright Rigueur, an assistant professor of public policy at Harvard's Kennedy School of Government, said African American political appointees often struggle to work effectively within Republican administrations whose policies are often antithetical to the demands of black communities.
"Even though she had access and was touting herself as this powerful figure," she said, "that power really meant nothing because she didn't have the power to influence Donald Trump, at least publicly, on issues she professed to care about and on issues that black people said they cared about."
In April, Manigault, who is also an ordained minister, married John Allen Newman, who at the time was pastor of a church in Jacksonville, Fla., at Trump International Hotel in downtown Washington. Trump did not attend the wedding.
Williams, the businessman, said Manigault had planned all along to stay only a year in the job, but he acknowledged that she clashed with Kelly.
"You have to remember, there was a time when Omarosa was one of the few people who could walk right into the president's office," Williams said. For Kelly to try to limit her access to Trump "is a big deal. She's in-your-face. She's the female Donald Trump. There's a price you pay when you have a Trump personality and don't have the power to go along with it."
Josh Dawsey contributed to this report.