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As Mr. Obama was 90 minutes late for the event, a couple of photographers stepped out a side door for a smoke. They were immediately ordered back into the theater by agents. Inside, one photographer was told he could not even carry a cup of coffee in the theater.

Photographers have long complained about the aggressive tactics of Mr. Obama’s protectors, saying they flank him at every stop, making photographs difficult. Some say they have been strong-armed by agents, pushed out of prime picture perches for security reasons.

The senator’s prospects and popularity are rising quickly, creating new problems for his security detail. On Friday, hundreds of people gathered to see Mr. Obama went into a frenzy even before he came into the room, chanting the senator’s signature phrase: “Fired up! Ready to go!”

An event organizer then said over a loudspeaker: “Ladies and gentleman, for security seasons, please take your seats.”

Brian DeBose and Christina Bellantoni contributed to this report.