If you’re trying to step away from the controversy of a contentious primary fight and present a more presidential face to the electorate it is really not helpful to make a mistake like this. From Mother Jones, which broke the story Tuesday:

On Monday evening, California’s secretary of state published a list of delegates chosen by the Trump campaign for the upcoming Republican presidential primary in the state. Trump’s slate includes William Johnson, one of the country’s most prominent white nationalists…

Johnson leads the American Freedom Party, a group that “exists to represent the political interests of White Americans” and aims to preserve “the customs and heritage of the European American people.”

The Trump campaign is now backing away from Johnson and blaming his selection as a delegate on “a database error.” Here is the campaign’s full statement as reported by Business Insider:

Yesterday the Trump campaign submitted its list of California delegates to be certified by the Secretary of State of California. 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.

According to the Mother Jones report, Johnson outlined his background in his application to be a delegate but avoided the phrase “white nationalist.” (White nationalists have recently begun rebranding themselves as “white advocates.”)

Johnson says that in his application to be a delegate for Trump he disclosed multiple details about his background and activism, though he did not specifically use the term “white nationalist.” The Trump campaign and Lagomarsino did not immediately respond to requests for comment. Whether or not Johnson was vetted by the Trump campaign, the GOP front-runner would have a hard time claiming ignorance of Johnson’s extreme views: Johnson has gained notice during the presidential primary for funding pro-Trump robocalls that convey a white nationalist message. “The white race is dying out in America and Europe because we are afraid to be called ‘racist,'” Johnson says in one robocall pushed out to residential landlines in Vermont and Minnesota. “Donald Trump is not racist, but Donald Trump is not afraid. Don’t vote for a Cuban. Vote for Donald Trump.”

In addition to the robocalls on Trump’s behalf, the campaign has already returned a check for $250 sent by Johnson, suggesting that someone in the organization must know who Johnson is and that he has already been the cause of negative press attention for the campaign.

Trump has distanced himself from the support of David Duke and the KKK. However, there was an awkward moment in February when Trump hesitated to denounce Duke during a TV interview on CNN. Trump later blamed the error on a faulty earpiece. However, that interview led to Speaker Paul Ryan coming forward and saying (without mentioning Trump by name) “If a person wants to be the nominee of the Republican party, there can be no evasion and no games. They must reject any group or cause that is built on bigotry.” Ryan added, “This party does not prey on people’s prejudices.” Clearly some of the white nationalists eager to support Trump have not yet gotten that message.

And there is one final wrinkle which could insure this mistake continues to dog Trump through the convention:

NEW: White Nationalist William Johnson remains on Trump's delegate list. Statement from CA Secretary of State Spox: pic.twitter.com/v7DNg0QE7v

— Candace Smith Chekwa (@CandaceSmith_) May 11, 2016