"We've talked about this," says Joel Hunter, evangelical pastor of Northland, a Church Distributed in Longwood, Fla., who prays with the president and writes some of the devotionals that DuBois sends. "It turns into a circus, and he feels badly about that."
Though Obama attends church on trips to Camp David, he rarely does so outside the presidential retreat in Maryland.
But Obama, says Hunter, "has found a way to get what he needs on a private basis."
In his formal position, DuBois coordinates the work of faith-based centers within 12 federal agencies, and he directs groups tackling such issues as teen pregnancy, adoption and poverty.
In the process, he consults clergy leaders from all religious traditions.
"I believe we provide pastoral insight to the president," said the Rev. Samuel Rodriguez, president of the evangelical National Hispanic Christian Leadership Conference. "Joshua helps us to do that."
DuBois says he primarily conveys their thoughts to the president's senior team, working up the food chain through his direct supervisor, domestic policy chief Melody Barnes. But informally, he has a direct line to the president. This spring, as the two rode in a limousine, they talked about the victims of a West Virginia mine explosion.
DuBois brought up the "valley of the shadow of death" in the 23rd Psalm. When Obama spoke to the miners' families, he quoted the passage.
DuBois usually prays with the president by speaker phone from his office at Jackson Place, a White House annex. Frequent guests are Bishop Charles Blake of the Church of God in Christ, a conservative-leaning church, and the Rev. Sharon Watkins, head of the more progressive Christian Church (Disciples of Christ).
"I get them on the phone," DuBois says of the other ministers, "but their connection is with the president. They're friends of his now. They know his heart."
And then there are the devotionals, the private messages of faith sent each morning about 6:30 to Obama's BlackBerry.
DuBois chooses passages from religious texts that range from the Bible to the Anglican Book of Common Prayer to meditations by established writers. Lately, he has consulted the classic collection of meditations "My Utmost for His Highest," by turn-of-the-century evangelist Oswald Chambers.
When asked, DuBois will pray with colleagues, in the office stairwell or at their homes. He is sometimes accompanied by his girlfriend of six years, an attorney at the Department of Justice, and, before her, the cats he hated to leave alone at his apartment. (His girlfriend is allergic to the cats. High Five and Shirley now live with another staffer.)
DuBois seems to anticipate moments of need, says Ashley Tate-Gilmore, who was Obama's Senate assistant and now works in the White House travel office.
Obama would say, "Let's get Joshua in here," she says, and DuBois was often there before she looked up from the phone.
On stage at the community center, Obama is speaking about responsible fatherhood, a topic of special importance to him. His father left when he was a toddler.
"We know that when fathers abandon their responsibilities, there's harm done to those kids," Obama tells the audience. "It's something that leaves a hole in a child's life that no government can fill."
Heads nod. One of them is DuBois'.
After his parents' marriage ended, DuBois and his mother struggled at times.
Shortly after learning that his father had died, in 2006, DuBois was called to the senator's office. Obama put an arm around him and offered words of comfort.
DuBois says he was drawn to Obama partly because of that personal affinity, but also by his view that problems like parental absence, poverty and abortion are interwoven with values and culture. He liked Obama's belief that effective solutions involve religious leaders.
Faith-based organizations "are on the front lines of some of the most difficult challenges we're facing as a nation," DuBois says. "This is driven by need."
When Obama finishes his speech, DuBois walks with him toward the back driveway and watches the motorcade pull away, lights flashing.
DuBois heads back inside to close out the event. The congregation is leaving the auditorium, and he wants to be there.