In naming Stephen K. Bannon to a senior White House post, President-elect Donald J. Trump has elevated the hard-right nationalist movement that Mr. Bannon has nurtured for years from the fringes of American politics to its very heart, a remarkable shift that has further intensified concern about the new administration’s direction.
The provocative news and opinion website that Mr. Bannon ran, has repeatedly published articles linking migrants to the spread of disease. Its authors have criticized politicians who do not support a religious test for immigrants to screen out potential jihadists. And it has promoted stories that tried to tie Huma Abedin, a top aide to Hillary Clinton who is Muslim, to Islamic militants.
In an interview, Mr. Bannon, 62, rejected what he called the “ethno-nationalist” tendencies of some in the movement. His interest in populism and American nationalism, he said, has to do with curbing what he sees as the corrosive effects of globalization. And he believes his enemies are misstating his views and those of many Trump followers.
“These people are patriots,” he said. “They love their country. They just want their country taken care of.”
He added, “It’s not that some people on the margins, as in any movement, aren’t bad guys — racists, anti-Semites. But that’s irrelevant.”
Some of Mr. Bannon’s own statements and behavior have drawn the condemnation of faith leaders and anti-discrimination groups, which reacted to his appointment with alarm on Monday. Jewish groups pointed to allegations from Mr. Bannon’s ex-wife that he had made anti-Semitic comments about the students at his daughter’s school. Critics have resurfaced other episodes from his past, including a 2011 interview in which he mocked liberals who criticize conservative women as “a bunch of dykes that came from the Seven Sisters schools.”
Mr. Bannon’s ascent has quickly become the focus of those critics, who broadly condemned the choice as divisive, if not racist, on Monday. But it was also a victory of head-spinning dimensions for a man who is relatively new to the president-elect’s inner circle. When Mr. Bannon joined Mr. Trump’s sputtering presidential campaign in August, he insisted to his friends that even if Mr. Trump lost, he could at least mitigate any damage to the nationalist movement, which he helped fuel as the head of Breitbart.
Instead, that nationalist movement — which has promoted and enabled anti-immigrant, anti-Muslim and racist sentiments — will now have a champion at Mr. Trump’s side in the West Wing.
The place that Mr. Bannon will occupy in the new administration, as senior counselor and chief strategist, also elevates to one of the most powerful roles in government someone whose mission in politics has been to tear down institutions, not run them.
His appointment was intended to be a reassuring signal to the vocal and restive members of Mr. Trump’s populist, anti-Washington base who are suspicious of power and anyone who holds it. Mr. Trump is their champion, but Mr. Bannon is their check against the Washington establishment and any efforts it makes to soften the new president’s resolve.
Mr. Bannon does not come out of the usual political or ideological backgrounds that have shaped the Republican Party in recent decades. He is not a religious conservative who is focused on social issues. He is not a traditional economic conservative. What especially motivates Mr. Bannon, his friends and colleagues say, is a sense that the country’s cultural and political elite are contemptuous of ordinary Americans. That endeared him to Mr. Trump, who never felt he received the respect he deserved for building such a large political movement.
That “arrogance of the elites,” as Mr. Bannon has said, explains why most of the media and political class missed the rise of Mr. Trump.
Mr. Bannon’s disgust with the politics of the mainstream Republican Party burns just as hot as, if not hotter than, his animus toward liberals. He sees Republicans as the “party of Davos donors” and has scorned them for denigrating Trump supporters as the “vulgarians, the hobbits” and “the peasants with the pitchforks.”
He is close to Sarah Palin, and at one point he urged her to take up the kind of Republican versus Republican battle he relishes: a primary campaign against Senator John McCain, her 2008 running mate. (She declined.) He was behind some of the Trump campaign’s most inflammatory moves, like inviting several women who had accused Bill Clinton of sexual advances to sit in Mr. Trump’s family box during a debate.
He had never worked on a national campaign until signing on with Mr. Trump, and has had eclectic taste in careers. He served as a Navy officer and went into banking for Goldman Sachs. He also helped run Biosphere 2, the domed ecosystem in Arizona where people lived without contact with the outside world. Like many leaders of the emerging hard-right movement, he became engaged in politics with the rise of the Tea Party early in President Obama’s first term.
He felt that the government’s bailout of the banking system was an egregious misuse of taxpayer dollars that did almost nothing to help ordinary Americans. His reason was personal: His father, a former telephone company lineman, had to sell off stock in his retirement account to make ends meet.
Mr. Bannon has told people in Mr. Trump’s inner circle that the new administration will have a short window of time to push its agenda through and should focus first on the priorities that are expected to be the most contentious.
Ever hungry for political combat, Mr. Bannon is expected to be an unrelenting advocate for many of Mr. Trump’s most aggressive plans on immigration. That involves stopping the immigration of Syrian refugees, deporting undocumented immigrants with criminal records and devoting more resources to securing the border.
Mr. Bannon, who grew up in a working-class neighborhood in Norfolk, Va., earned degrees from Georgetown and Harvard. He often compares Mr. Trump’s political rise to that of Andrew Jackson, the military general and populist hero who took on the political and social elite of his day as the seventh president of the United States.
While Mr. Trump became the leader of the movement of disaffected Americans who feel lost and disenfranchised in a nation undergoing rapid cultural and demographic change, Mr. Bannon has been a student of global populist trends, carefully tracking the rise of the far-right National Front in France under Marine Le Pen and the remarkable victory of the U.K. Independence Party in Britain’s vote this year to leave the European Union.
“Steve saw — and was a thought leader and a visionary about — the issues and the movement that Trump eventually caught on to and espoused,” said Larry Solov, the chief executive of Breitbart.
“He’s like a field general,” Mr. Solov added, “and very much sees the fight for the soul of this country as a war.”
Mr. Bannon will take his White House job already at odds with the House speaker, Paul D. Ryan, an ally of Mr. Priebus’s whom Mr. Bannon has long sought to undermine. When he ran Breitbart, Mr. Bannon promoted Mr. Ryan’s opponent in the Wisconsin primary in the website’s news stories and radio interviews. Mr. Bannon is personally close to members of Congress like Dave Brat, the Virginia Republican who unseated Eric Cantor, the former majority leader. He has written that the appropriations process under Mr. Ryan was “a total and complete sellout of the American people.”
His former colleagues at Breitbart refer to him admiringly as a “honey badger” because of his relentlessness — a quality they now expect him to turn on Washington.
“What drives Steve,” said Joel B. Pollak, Breitbart’s editor at large, “is the way the political establishment is holding back American politics.”