Doug Jones makes a campaign stop in Troy, Ala., on Nov. 17. The Democratic candidate for U.S. Senate believes he can win if he pieces together an unusually delicate coalition. (Aly Grice/Troy Messenger/AP)

The Ensley Park Recreation Center was beginning to come to life. The song "Happy" and other upbeat tunes boomed through the loudspeakers. And a crowd was gathering for a chance to glimpse something rarely seen in conservative Alabama: a surging Democratic candidate for U.S. Senate.

But Donald Williams was skeptical.

The 75-year-old retired UPS worker had come to cheer on Democrat Doug Jones in a campaign that has captured national attention. Has it also generated energy in Alabama’s African American communities?

“As of this day, I would say no,” said Williams, who is black. “And this is Doug Jones’s problem. He’s got to get out and get the voters energized.”

With two-and-a-half weeks left until Election Day, a once unthinkable victory in the heart of the Deep South is within Jones's reach, thanks largely to a string of sexual misconduct allegations against Republican candidate Roy Moore.

Jones’s campaign believes he can win only if he pieces together an unusually delicate coalition built on intense support from core Democrats and some crossover votes from Republicans disgusted with Moore. Crucial to that formula is a massive mobilization of African Americans, who make up about a quarter of Alabama’s electorate and tend to vote heavily Democratic.

Yet, in interviews in recent days, African American elected officials, community leaders and voters expressed concern that the Jones campaign’s turnout plan was at risk of falling short.

“Right now, many African Americans do not know there is an election on December 12,” said state Sen. Hank Sanders (D), who is black and supports Jones.

The challenge for Jones is clear. According to Democrats working on the race, Jones, who is white, must secure more than 90 percent of the black vote while boosting black turnout to account for between 25 and 30 percent of the electorate — similar to the levels that turned out for Barack Obama, the country’s first black president.

As a result, Jones and his allies are waging an aggressive outreach campaign. It includes targeted radio and online advertisements, billboards and phone calls. Campaign aides are debating whether to ask former first lady Michelle Obama to record a phone message for black voters.

The message emphasizes that Jones prosecuted two Ku Klux Klan members who bombed a black church in Birmingham in 1963.

The Jones campaign expects to intensify its black outreach in the final stretch. Among the messages under consideration for radio ads and already included in mailers that have been produced, according to campaign officials, are reminders that Moore once opposed removing segregationist language from the state constitution and expressed doubt that Obama was born in the United States.

The Moore campaign did not respond to a request for comment.

A key question for Jones's campaign is how to balance a more partisan campaign message aimed at energizing core Democrats, particularly blacks, with the need to appeal to GOP voters with a more middle-of-the-road approach. Not only must Jones come close to matching Obama's performance among blacks, but also he must far surpass the former president's tallies among whites. Exit polls show that Obama won 15 percent of the white vote in Alabama in 2012 — and Jones, according to Democratic strategists working on the race, may have to win more than a third of white voters to beat Moore.

The accusations Moore is facing from women who said he made unwanted sexual contact with them when they were teenagers and he was in his 30s, including one who said she was 14, have opened the door for Jones to peel away some of these Republican votes. Moore, 70, has denied the allegations, and his allies have argued that even skeptical GOP voters should back him because he will be a reliable conservative vote.

Maximizing black turnout “makes the rest of what he needs to do more achievable,” said Zac McCrary, a Democratic pollster whose firm is working on the race for the Democratic Senatorial Campaign Committee.

The Democratic nominee does not appear to be lacking in resources to make a closing pitch to black voters. According to a Democrat and Republican tracking the ad war, both of whom spoke on the condition of anonymity to describe their findings, Jones is on pace to spend more than $4.7 million on ads between early October and Election Day, compared with about $636,000 by Moore and an allied group.

The Jones campaign said it has placed about 40 billboards across the state, some of which show photographs of the four young black girls who were killed in the 1963 church bombing.

One recent ad on R&B radio recounts Jones's closing arguments as the lead prosecutor in the case.

Meanwhile, the campaign is targeting online ads at younger African Americans by focusing more on jobs and education.

"Turnout for a special election is a problem across the board, and we are putting as many resources as we can behind making people aware not only that there's an election, but with the opportunity that Doug Jones presents for Alabama," said Giles Perkins, the chairman of the Jones campaign.

At a stop here in Birmingham last week, a fish fry held inside a rec center gym, Jones presented himself to the crowd as a break from Alabama’s painful past.

Jones said the differences between him and Moore “could not be greater,” and he encouraged backers to spread the word about the election.

“We are at a tipping point,” he told the crowd. Jones later added: “We are on the right side of history in this campaign.”

Jones, 63, is getting an assist on the campaign from elected officials and organizations that are prominent in the African American community.

He was joined at the fish fry by Randall Woodfin, the 36-year-old mayor-elect of Birmingham and a rising political star in the state.

Rep. Terri A. Sewell, who is African American and the only Democratic member of the state’s congressional delegation, said she recently took Jones through six churches in her home town of Selma — and sought to introduce Jones as an effective advocate for their community.

“Doug is not a default candidate,” Sewell said.

The Alabama chapter of the NAACP is also helping inform voters about Jones, even as it is not officially endorsing a candidate in the race. Benard Simelton, the president of the Alabama State Conference of the NAACP, said in an interview his group is making phone calls to what he termed “sometimes voters,” meaning those who tend to vote only in presidential elections.

NAACP volunteers read from a script that tells voters that Jones prosecuted members of the KKK and that Moore has twice been removed from the state Supreme Court and has said that Muslims should not serve in Congress, Simelton said.

But Simelton voiced some reasons for concern that black turnout may not be as high as it needs to be for Jones.

“I hate to say it: A lot of people are apathetic about voting, because they don’t think their vote counts,” he said.

Simelton also said the NAACP was trying to encourage college students to vote, but that the effort might have “missed the boat a bit” on that front when schools closed for Thanksgiving ahead of the Nov. 27 registration deadline.

Kyle Campbell, 21, a University of Alabama law student who has been actively involved in Democratic politics in recent years, said in an interview that energy in his circles for the election is on par with a presidential race.

“Every young, black voter that I talked to who voted in 2016 is going to vote in this election,” Campbell said.

For Campbell, the election could be a personal turning point in deciding whether to stay in Alabama long-term or move to another state.

“If Roy Moore actually did win — I couldn’t make any promises about it — but it would be very difficult for me to see the potential for Alabama, even as someone who has lived here most of my life,” he said.

Michael Scherer contributed to this report.