Lawyer William Johnson, a leader of the American Freedom Party and a self-proclaimed white nationalist who supports Donald Trump, pauses for photos in his office in Los Angeles on May 10. (Jae C. Hong/Associated Press)

A prominent national white supremacist leader has resigned as a Donald Trump delegate to the Republican National Convention after campaign officials said his nomination was the result of a “database error.”

William Daniel Johnson, who has called for a whites-only United States and the deportation of other races and ethnicities, said in an interview Wednesday that he resigned for the good of the Trump campaign, which he supports.

“They don’t need the baggage that came along with my signing up as a delegate,” said Johnson, a Los Angeles corporate lawyer who has been active in U.S. white supremacy circles for more than three decades.

Johnson’s name was included in a slate of delegates that the Trump campaign submitted Monday for certification by the California secretary of state’s office.

After Mother Jones magazine reported Johnson’s inclusion on the list, Trump officials moved quickly to remove him. Campaign spokeswoman Hope Hicks told The Washington Post that “a database error led to the inclusion of a potential delegate that had been rejected and removed from the campaign’s list in February 2016.”

Johnson, who has said that U.S. citizenship should be limited to white people with “no ascertainable trace of Negro blood,” said he believed the Trump campaign staff members who added his name to the list were unaware of his white supremacist beliefs.

“I was a delegate for two hours, they got inundated, and that’s probably the time they said, ‘Who is this Johnson?’ ” he said. “Nobody knows who I am. I think the Trump campaign probably knows more about me now, but you can’t hold that against the vetting people in a campaign. I didn’t emblazon on there that I’m a white nationalist. So it was an innocent mistake on the vetting person’s part.”

California Republican Party bylaws permit campaigns to amend their delegate lists until June 27, when those lists are submitted to the Republican National Committee, party spokeswoman Kaitlyn MacGregor said.

Heidi Beirich of the Southern Poverty Law Center, which monitors extremism, said it is hard to believe the Trump campaign was not aware of Johnson’s beliefs. She noted Johnson’s long history of high-profile white supremacist activism, and the fact that he founded the pro-Trump American National super PAC and that he has actively campaigned for Trump.

Earlier this year, Johnson recorded robo-calls supporting Trump that were used ahead of the Republican primaries in Iowa, New Hampshire, Vermont and Minnesota.

In those calls, which received extensive national media attention, Johnson said, “The white race is dying out in America and Europe because we are afraid to be called ‘racist,’ ” warned of the “gradual genocide against the white race” and complained that in the United States, “few schools anymore have beautiful white children as a majority.”

“Donald Trump is not a racist, but Donald Trump is not afraid,” he said. Then, referring to Sen. Marco Rubio (R-Fla.) and Sen. Ted Cruz (R-Tex.), both of whom are children of Cuban immigrants, he said: “Don’t vote for a Cuban. Vote for Donald Trump.”

Johnson, who has a law degree from Columbia University, said that the Trump campaign had not authorized the calls. He gave out his cellphone number and asked people to call him if they wanted.

Beirich called the Trump campaign’s inclusion of Johnson as a delegate “despicable.”

“There’s no way to not have known this; those robo-calls have been all over the press for months,” she said. “You have to wonder about the campaign’s competence, or if this is once again pandering in some way to white supremacists.”

Throughout his campaign, Trump has battled the perception that he has been at least tacitly sympathetic to white supremacists. He appeared slow to repudiate former Ku Klux Klan leader David Duke after Duke praised him, and he has retweeted messages from white nationalists.

Beirich said that Trump had been careful not to offend white supremacists during the Republican primary campaign. She said she expected him to moderate his tone in the general-election campaign, but she said she found it hard to believe that any candidate would want the support of people with Johnson’s views.

“It’s 2016. Nobody appeals to white supremacists,” she said. “This is the worst of American history. This is fire hoses and dogs being sicced on black people who want the right to vote — this is what this represents. This is unacceptable.”

Johnson said he has been a leading voice of white supremacy since at least 1985, when he wrote a book proposing a constitutional amendment that would have limited U.S. citizenship to “non-Hispanic whites of the European race, in whom there is no ascertainable trace of Negro blood, nor more than one-eighth” any other nonwhite race or ethnicity.

He proposed that some “Hispanic whites” would be eligible for U.S. citizenship provided “they are in appearance indistinguishable from Americans whose ancestral home is in the British Isles or Northwestern Europe.”

Johnson has run for Congress in Wyoming and Arizona and a judgeship in California, and he has raised money for the presidential campaign of former congressman Ron Paul (R-Tex.). His campaigns have been based on “white nationalist” platforms, and he has even complained about fictional character Harry Potter kissing a “Chinese girl” in a movie, according to the Southern Poverty Law Center.

However, Johnson has said on his law firm’s website that he has long represented Japanese corporations doing business in the United States, and that he can “speak, read and write Japanese.” The website is written mainly in Japanese, and Johnson speaks in Japanese in a video on the site. Johnson notes that he is looking for new Chinese clients.

Johnson said he supports Trump because “he speaks his mind.”

“He won’t govern by public opinion poll; he will speak what he thinks is right,” Johnson said. “I believe Ron Paul was that way, I believe [Democratic candidate] Bernie Sanders is that way. And regardless of your political beliefs, that is a refreshing change.”

Johnson, who said his American Freedom Party has experienced an increase in recruitment because of Trump, said he likes Trump’s positions on “securing our borders and keeping the jobs back in America.”

But he said he doesn’t think that Trump supports white supremacist causes.

“I believe he does not,” Johnson said. “It’s unrequited love.”

Johnson, whose proposed 1985 constitutional amendment would have denied U.S. citizenship to anyone who was more than one-eighth “Semitic,” said he is not bothered that Trump’s daughter Ivanka converted to Judaism when she married an orthodox Jewish man.

“I do think it’s better for a Christian to marry a Christian,” he said. “But that’s not my say, and it’s not Donald Trump’s say. That’s his daughter’s say.”