AUDIE CORNISH, HOST:
Neurosurgeon Ben Carson is running for president, and he's also selling his new book. And as NPR's Sam Sanders reports, sometimes the line between book tour and campaign gets a little blurry.
SAM SANDERS, BYLINE: The mood at Ben Carson's book tour events has been something in between a church revival and a rock concert, with reactions like these from Addy Earhart (ph).
ADDY EARHART: I was shaken.
SANDERS: You were shaken.
SANDERS: Why were you shaken?
EARHART: I was just so nervous.
SANDERS: She was like a teenage fan meeting a Taylor Swift or a One Direction. At every event, there are attempts at weird quick hugs, selfies taken before handlers quickly push fans away and tears, like from Kathy Yosten.
KATHY YOSTEN: I love that man. He's wonderful. He's calm. He's intelligent. I see a goodness in his eyes. He makes me feel safe.
SANDERS: You're tearing up right now. He means a lot to you.
YOSTEN: Yes, he does.
SANDERS: Also declarations like this from Beverly Belew in Fort Worth.
BEVERLY BELEW: Oh, my heart was racing just to see his face, to walk up there and his smile. He smiled at me, and he said, welcome. And I said, I love you, Dr. Carson (laughter).
SANDERS: And what did he say back?
BELEW: And he said thank you.
SANDERS: The rockstar nature of adoration at these events even extends to Dr. Carson's wife, Candy. At a bookstore in Waco, I heard a woman come up behind me and say this.
SHERRY BAKER: Oh, my God, she was in the bathroom - Ms. Carson.
SANDERS: Who was in the bathroom?
BAKER: Ms. Carson, Ms. Carson.
SANDERS: You got a picture with Ms. Carson in the bathroom.
BAKER: (Laughter). I did.
SANDERS: That was Sherry Baker proudly showing off a selfie she had just taken with Carson's wife. She had cornered her in the women's restroom.
SANDERS: From Bryan to Waco to Fort Worth to Plano, the lines of fans are hundreds deep. There's constant applause and cheers. But here's the thing. Dr. Carson is usually the quietest man in the room.
BEN CARSON: How are you?
UNIDENTIFIED MAN: Thanks for running.
CARSON: OK, absolutely.
SANDERS: Most of the time, his voice is barely above a whisper. The other thing to know about these Carson book tour events is that they are not officially campaign events. Legally, Carson can't use campaign funds or staff or even his official campaign bus to do book tour stuff.
CARSON: We do some book events, and we do some campaign events. We separate the staffs. We separate the funding so that there are no FEC violations.
SANDERS: So Carson has a book tour bus, and staff from his book publisher travel with him. But there's another bus at every stop courtesy of Carson's super PAC with volunteers like Kenn Farr. He's signing up more volunteers for the super PAC. Farr says he and other Carson supporters really propelled Carson into a run in the first place.
KENN FARR: He's not sought the office his whole life. We drafted him. We asked him, hey, will you go do this for us?
SANDERS: At every stop, Carson is asked questions about his policies, his run for president, and he answers those questions like how he'd fix the economy.
CARSON: The economy grew at a rate of 3.3 percent since 2001. In 2014, it grew at a rate of 1.8 percent. That's a huge difference. The GDP-to-debt ratio is 103.
SANDERS: Even Carson admits sometimes it's hard to separate the campaign from the book tour.
CARSON: Honestly, anything that you do when you're running for president is campaigning, to a sense, because it's going to be seen that way.
SANDERS: Whether these events are campaign or book tour or a bit of both, they always end the same way. Carson takes photos with the book store staff and the police detail, and usually, as he exits the store, there are more cheers.
SANDERS: Carson enters the tour bus, the bus with his face plastered on the side. More photos are snapped, and as he rolls out of the parking lot, his fans wave and cheer some more. It's hard to tell in moments like this whether those fans are there for Ben Carson the author, the candidate or both. Sam Sanders, NPR News, Dallas. Transcript provided by NPR, Copyright NPR.