In this Sept 4, 2017 photo, Justin Fairfax, right, Democratic candidate for lieutenant governor. speaks at a Democratic breakfast with, from left, Attorney General Mark Herring, gubernatorial candidate Lt. Gov. Ralph Northam and U.S. Sen Tim Kaine in Buena Vista, Va. (Bob Brown/AP)

Virginia Democratic gubernatorial hopeful Ralph Northam omitted any mention of Justin Fairfax, the party's African American candidate for lieutenant governor, from about a thousand pieces of campaign literature, which Fairfax called a "mistake." The incident has stoked tensions within the Democratic ticket, threatening to alienate African American voters three weeks before Election Day.

The palm cards with photos of Northam and Attorney General Mark R. Herring (D) were produced for canvassers with the Laborers' International Union of North America (LIUNA), which asked that Fairfax be excluded because it did not endorse him. Fairfax has spoken critically of two proposed natural gas pipelines that the union supports.

The literature was a sliver of the 1.5 million pieces produced by the Northam campaign, and homes that received palm cards without Fairfax also received literature with the entire ticket, the Northam campaign said.

Nevertheless, a photo of two palm cards — one with and one without Fairfax — made its way around social media this week and provoked outrage.

"It reeks of subtle racism, if not a tone deafness about how we are going to win in November," said Quentin James, the founder of Collective PAC that supports black candidates, including Fairfax. "Leaving Justin Fairfax off . . . even if it's only for a small universe of union members, still sends the wrong message."

In an interview Wednesday, Fairfax called the move to exclude him a "mistake" by the Northam campaign but wouldn't call it racism.

"Everyone who is looking at this will make their own judgments about this particular instance," he said. "This should not have happened, and it should not happen again, and there needs to be robust investment in making sure that we are communicating with African American voters and we are engaging our base."

Hours later, Fairfax's campaign released a more conciliatory statement.

"This is a strong ticket and one that is working well together," it said. "One piece of literature does not change that. Voters from across the commonwealth have responded enthusiastically to Justin's candidacy and the entire Democratic ticket. They are excited about our plan to offer more educational opportunity, economic growth, and more access to health care and they will reject the divisive and cynical politics of our opponents. That's why Justin's been endorsed by organizations like the VA AFL-CIO, Virginia Education Association and Planned Parenthood Advocates of Virginia."

Some black leaders called the issue a distraction.

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"Democrats, particularly minority Democrats, need to stay focused on the goals, and the goal is to make sure Justin wins, that Ralph wins, that Mark wins," said Andrea Bailey of the Prince William County NAACP.

The dust-up comes the day before former president Barack Obama is scheduled to headline a rally in Richmond with Northam, Fairfax and Herring. Obama's appearance, at the city's convention center, is designed to motivate the Democratic base, particularly African American voters.

Most polls have shown a tight contest between Northam and Republican Ed Gillespie. Virginia is holding the nation's only competitive statewide contest, which is being closely watched as a hint of what's to come in next year's midterm elections.

Fairfax would be the first African American elected statewide in Virginia since L. Douglas Wilder became the nation's first elected black governor in 1989. Blacks make up roughly a fifth of the Virginia electorate and are crucial for Democrats to win statewide.

Fairfax and Northam discussed the matter over the phone Tuesday, both campaigns confirmed.

A spokesman for Northam said the exclusion of Fairfax from the palm cards was not meant as a snub. "We are committed to winning all three statewide offices and will continue to work together — as we have been working together — throughout the final weeks of the campaign," Northam campaign spokesman David Turner said.

LIUNA did not respond to questions about its canvassing efforts, but it defended its decision to not endorse Fairfax.

"It is not in [members'] interest for us to back a candidate who has a record of opposing infrastructure projects that our members will work on and rely on to provide them with good family-supporting middle-class jobs," said Dave Allison, business manager for the union's Baltimore-Washington District Council.

Phillip Thompson, president of the Loudoun County NAACP, said the exclusion of Fairfax from literature reinforces a perception that the Democratic Party sees him as an outsider and is taking the black vote for granted.

"A lot of us feel the Virginia Democratic Party has never been a very inclusive group, and they always kind of marginalize African Americans without providing any grounds for advancement," said Thompson. "Hillary [Clinton] won the state of Virginia because of the African American, Hispanic and minority vote. . . . Justin is a perfect person to help them do that again, and they still don't support him."

Fairfax, a 38-year-old attorney from Fairfax County, ran for attorney general in 2013, largely unknown to Democratic Party insiders.

He narrowly lost in the primary and spent years cultivating relationships with party officials before his second statewide run. But tensions persisted, including when he was denied a speaking slot at a party convention in 2016.

Turner stressed that Northam has been working to help Fairfax and other Democratic candidates.

"Ralph Northam is making a historic investment in the coordinated campaign, including giving or raising $9 million in Get Out The Vote efforts for the entire ticket without asking for any additional investment from the ticket mates," Turner said.

Michael Halle, a political adviser to Gov. Terry McAuliffe (D) who ran the Democratic coordinated campaign in 2013, said the omission of Fairfax from the palm cards was being blown out of proportion. Democratic voters targeted by canvassers are inclined to vote for the entire ticket, and the full ticket often is not on literature — including Northam, when he ran for lieutenant governor in 2013, Halle said.

"The more important thing is getting people out to vote than who is on the piece of literature," Halle said. "There's no effect in mobilization from whose picture or whose name is on literature."

Virginia Republicans and conservative media outlets pounced Wednesday, highlighting the incident to emphasize intraparty divisions.

The GOP has also been accused of racially tinged attacks against Fairfax.

Fairfax's Republican opponent, Jill Holtzman Vogel, questioned whether he could "talk intelligently" about issues in their last debate — a comment that the chair of the Democratic Party of Virginia said belongs in 1957 instead of 2017.