Phillip E. Thompson, the president of the N.A.A.C.P. in Virginia’s Loudoun County, said he was worried that black voters were simply not engaged.
“I’m just not getting the vibe on it,” he said. “Not at all.”
Mr. Obama may be a draw, but there are limits to what he can accomplish as a surrogate campaigner during brief forays into electoral politics. Democrats recall too well the dip in black turnout in the decisive states of Michigan, Pennsylvania and Wisconsin that doomed Hillary Clinton last year. That same dip was partly to blame for the down-ballot losses that Democrats suffered earlier in Mr. Obama’s term.
Another slump in 2018 would imperil the party’s efforts to capture the House, hold its own in the Senate and win key governorships.
“If the party doesn’t change what they’re doing, we’re not going to take back the House, we’ll lose seats in the Senate and folks will come around after and say, ‘What happened?’” warned Representative Cedric L. Richmond of Louisiana, chairman of the Congressional Black Caucus. “We are doing a pathetic job of reaching out to minority voters.”
In both Alabama and Virginia, Democrats have tried to lay the groundwork for stronger black turnout in 2017 and midterms next year. Officials with the Democratic Congressional Campaign Committee briefed party strategists this month on plans to conduct research in several states, including New Jersey and Virginia, to identify issues most likely to motivate minority voting in 2018.
In Alabama, national leaders, including Senators Chuck Schumer and Bernie Sanders, have appealed to Mr. Woodfin to deploy his field organization to help Mr. Jones in the special election for the Senate.
Mr. Woodfin, a 36-year-old insurgent who toppled an incumbent Democrat this month, said he intended to help Mr. Jones, who convicted two Ku Klux Klansmen for a Civil Rights-era church bombing in his city. African-Americans are “looking for people to fight for their issues,” he said.
In Virginia, Mr. Northam has targeted black voters in the final weeks of the race, frequenting black churches and campaigning with Eric H. Holder Jr., the former attorney general, in addition to Mr. Obama.
But Mr. Northam’s overtures have been met with mixed results.
Kathy Harkless and two of her fellow congregants at First Mount Zion Baptist Church had just met Mr. Northam after he attended worship services here Sunday, but when asked about his bid for governor, they quickly steered the conversation toward Washington.
Credit Hiroko Masuike/The New York Times
“I don’t want what we have now,” said Ms. Harkless, referring to Mr. Trump. “It’s awful.”
It is a familiar refrain to Dr. Luke E. Torian, who divides his time pastoring the church, founded 150 years ago by former slaves, and representing parts of this Washington exurb in the state legislature.
“The lieutenant governor’s campaign has to make some of the current administration’s issues resonate,” he said. “That’s going to be his challenge.”
Mr. Northam seems well prepared to engage black residents. He attended integrated schools as a child on Virginia’s eastern shore and often worships at a black church when back home. He won African-American voters decisively in the Democratic primary this year, and has put opposition to Mr. Trump at the center of his message.
But Mr. Northam has also been uncertain about how to handle calls to remove Confederate statues in the state after the bloodshed in Charlottesville this summer, seemingly torn between not wanting to offend whites in this history-drenched state and not wanting to get crosswise with his African-American base. After initially saying he would be “a vocal advocate” for taking down the monuments, Mr. Northam, facing an onslaught of ads from his Republican opponent over the issue, said last week that he was “not going to meddle” with localities over the issue.
Some in the party wish Mr. Northam would more aggressively trumpet the candidacy of Justin Fairfax, 38, a lawyer and the Democratic nominee for lieutenant governor who could be the first black candidate elected statewide since 1989. And a growing chorus of black activists and strategists say the party’s church-focused appeals are not reaching younger African-Americans. Instead, they say, Mr. Northam needs to talk directly about sensitive issues like policing and criminal justice for blacks under 40 to turn out.
“The racial issues besieging communities of color are now competing with and in many ways trumping conventional general election issues,” Cornell Belcher, a Democratic pollster who is black, wrote in a memo that was forwarded to The New York Times.
He surveyed Virginia voters of color last month and found lagging interest among African-Americans in the race for governor.
Elected Democrats in Virginia suggest the anger toward Mr. Trump will ultimately translate into votes. “The national circus is overshadowing it, but if you’re on the doors like I am, you’re hearing that excitement and you’re hearing the people excited to vote,” said Marcia Price, a delegate.
The Alabama contest is even more delicate for Democrats, because of the state’s intensely polarized racial politics. But Democrats believe Mr. Jones has a slim path to victory.
To win, Mr. Jones must maximize turnout among the quarter of voters who are black, while capturing about a third of the overwhelmingly white Republican population. Democrats have little infrastructure left in the state. Old-guard black groups have withered, and Republicans have won every statewide office for a decade.
Mr. Jones has put his legal pursuit of the Klan at the center of his message and has reached out to leaders of the Congressional Black Caucus, including Mr. Richmond. Representative Hakeem Jeffries, Democrat of New York and a member of the House leadership team, said he met with Mr. Jones and was watching the race closely.
To turn out black voters in 2018, Mr. Jeffries said, Democrats would have to go beyond “doing drive-bys in African-American churches.”
“Those days need to be over if Democrats are serious about winning,” Mr. Jeffries said.
Mr. Holder, who served alongside Mr. Jones as a United States attorney, said he had spoken with Mr. Jones by phone and planned to host a fund-raising event for his campaign. Perhaps more tellingly, Mr. Holder said his wife, Sharon Malone, a prominent Washington obstetrician whose sister was the first black graduate of the University of Alabama, intended to campaign for Mr. Jones.
Mr. Holder said in an interview that Democrats had to balance their overtures to white voters who backed Mr. Trump with outreach to black voters.
“Certainly some attention needs to be focused there,” Mr. Holder said of Trump voters. “But that doesn’t mean that you don’t also focus on issues of particular concern to African-Americans.”