Here's what you need to know about the man who went from Breitbart News chairman to Donald Trump's campaign CEO before his appointment as chief White House strategist and senior counselor. (Jenny Starrs/The Washington Post)

This post has been updated.

President-elect Donald Trump's decision to appoint Stephen Bannon as his chief strategist in the White House has drawn a sharp rebuke from political strategists who see in Bannon a controversial figure too closely associated with the “alt-right” movement, which white nationalists have embraced.

Bannon, who was the executive chairman of Breitbart News before joining the Trump campaign in August, will serve as chief strategist and senior counselor for Trump; that will give Bannon authority over the strategic direction of the White House. Bannon will assume a similar role to that of Karl Rove during George W. Bush’s administration and recently by longtime strategist John Podesta under President Obama. He and Republican National Committee Chairman Reince Priebus, who will become White House chief of staff, will be among Trump's top advisers.

The announcement has produced intense hand-wringing in Washington and sharp denunciations from political observers and strategists critical of Breitbart News's close association with the alt-right, a fringe conservative movement saturated with racially insensitive rhetoric and elements of outright white nationalism.

The Southern Poverty Law Center, a hate-watch group, has accused Breitbart of explicitly embracing ethno-nationalism. After Bannon's elevation was announced, the law center tweeted several controversial stories written by Breitbart under Bannon's control, including a piece published two weeks after a mass killing at a black church in Charleston, S.C., last year: “Hoist it high and proud: the confederate flag proclaims a glorious heritage.”

“Stephen Bannon was the main driver behind Breitbart becoming a white ethno-nationalist propaganda mill,” the law center wrote via Twitter in its first statements on Bannon’s elevation. “Trump should rescind this hire. In his victory speech, Trump said he intended to be president for 'all Americans.' Bannon should go.”

Trump’s critics, across the political spectrum, immediately blasted the move on social media.

The Anti-Defamation League voiced its strong disapproval in a statement Sunday evening, calling Bannon's appointment "a sad day." "We call on President-elect Trump to appoint and nominate Americans committed to the well-being of all our country's people," said Jonathan Greenblatt, ADL's chief executive.

The Council on American-Islamic Relations also denounced the appointment and criticized Breitbart for trafficking "misogynistic and racist stories targeting women, people of color and immigrants."

"The appointment of Stephen Bannon as a top Trump administration strategist sends the disturbing message that anti-Muslim conspiracy theories and White nationalist ideology will be welcome in the White House," said Nihad Awad, CAIR’s executive director. "We urge President-elect Trump to reconsider this ill-advised appointment if he truly seeks to unite Americans."

Bannon’s personal history also has been mired in controversy. Shortly after he joined the Trump campaign, court documents revealed that his ex-wife, Mary Louise Piccard, had accused Bannon of domestic violence and anti-Semitic language in 2007. (The documents were obtained and first reported by the New York Daily News.)

“The biggest problem he had with Archer is the number of Jews that attend,” Piccard said in a statement to the court. “He said that he doesn't like the way they raise their kids to be 'whiny brats' and that he didn't want the girls going to school with Jews.” Bannon has denied the accusations.

Ben Shapiro, a former Breitbart editor who worked closely with Bannon, called him a “legitimately sinister figure” in an article he published on the Daily Wire after Bannon joined the Trump campaign.

“Many former employees of Breitbart News are afraid of Steve Bannon. He is a vindictive, nasty figure, infamous for verbally abusing supposed friends and threatening enemies,” Shapiro wrote.

During his campaign, President-elect Donald Trump repeatedly vowed to "drain the swamp" in D.C. and rid the federal government of political elites and lobbyists. But just days into his transition to president, Trump seems to be doing the opposite. (Deirdra O'Regan/The Washington Post)

Some of the Trump campaign's most controversial moves in the final months of the campaign were attributed to Bannon, who is known for his combative and unfiltered style. When Trump, before the second presidential debate, invited several women who had accused Bill Clinton of sexual misconduct to hold a news conference, Bannon stood in the back of the room smiling broadly.

“I want to thank President-elect Trump for the opportunity to work with Reince in driving the agenda of the Trump Administration,” Bannon said in a statement released by the campaign Sunday. “We had a very successful partnership on the campaign, one that led to victory. We will have that same partnership in working to help President-elect Trump achieve his agenda.”

Bannon's appointment brings into focus many of the uncomfortable racial tensions surrounding Trump's campaign, stemming from Trump’s staunch anti-immigrant rhetoric. Throughout the election, Trump's critics accused him of using such language and the politics of racial grievance to motivate his supporters, charges that he has denied and dismissed. In an interview with CBS's "60 minutes” that aired Sunday, he expressed surprise when asked about racial slurs that were being used against African Americans and other minority groups since his election.

“I am very surprised to hear that. I hate to hear that, I mean, I hate to hear that,” Trump said in the interview, which was taped Friday. "I would say don't do it, that's terrible, because I'm going to bring this country together.

“I am so saddened to hear that. And I say stop it, if it helps. I will say this, and I will say right to the cameras: Stop it,” Trump added.