He’s been asked to stay inside. Why? He will literally stop traffic.

“I would love to say hello to them, but they’ve advised me for traffic purposes and other reasons that it’s best not to go out,’’ says the youngest of the three heartthrob Jonas Brothers singer-songwriting siblings in his dressing room. “It could get interesting.’’

Downstairs and outside on 45th Street, scores of tweens and teens wait in vain for Jonas to emerge after his afternoon show. But it’s a Wednesday — one of two matinee days — and all he can do is shower, sip coffee and check messages on his phone.

Michael Urie, the former “Ugly Betty’’ actor who stars alongside Jonas in the musical, says that when he steps outside the theater, the crowd asks two questions. The first: “Is Nick coming out?’’ followed by “Will you go back in and tell him to come out’’

“I have never met anyone who has gobs of fans like Nick does,’’ says Urie. “He is so incredibly aware of them, respectful of them and gracious with them. He always stops to talk with them and take photos.’’

Jonas, 19, has just finished his 34th show as the amoral corporate climber J. Pierrepont Finch, having taken over the part from Darren Criss of Fox’s hit show “Glee,’’ who briefly assumed the role from Daniel Radcliffe.

The no-meet-and-greet-fans policy was installed during Radcliffe’s reign, a 10-month triumph that packed the theater and earned the “Harry Potter’’ star new respect for his energy and enthusiasm.

Jonas, who is committed to playing the song-and-dance part until at least July 1, has seen the show’s box office suffer a little in the wake of Radcliffe’s departure, but says he feels a different sort of pressure.

“The pressure comes in knowing how big a role this is, how big an opportunity this is, knowing that it’s the kind of role that you need to take ownership of and really command,’’ he says. “That’s where the pressure comes from, I’d say, not so much from previous Finches or productions or anything like that. It’s the kind of pressure that pushes you to be better, which I think is always the good kind of pressure.’’

Fans who miss seeing Jonas on matinee days can see him on television. He makes a guest appearance Monday night on the NBC series “Smash,’’ a behind-the-scenes look at the making of a Broadway show.