CHARLOTTE, N.C.—On Tuesday, a group of more than 100 protesters shouting "Obama is a traitor" temporarily shut down official bus service that ferries around delegates at the Democratic National Convention. The protesters, some of whom were lying down in the street, were surrounded by Charlotte police, who used their bicycles to build a barrier around the group.

"What do you think of free speech zones?" shouted one protester to the police and onlookers, referring to the cordoned-off areas for activists. "Does that seem strange to you?" Protesters also shouted that accused WikiLeaks source Bradley Manning should be freed. At one point, the protesters raised a tent above their heads and set it on the ground. "Bad news, guys, they've pitched a tent," a police officer joked. "They might be here for the duration."

Delegates and convention goers who were forced to wait for buses to be rerouted expressed surprise that the Occupy presence has been stronger at the DNC than at the Republican convention in Tampa last week. "I didn't see them at the Republican convention," said Wandra Ashley-Williams, vice president of the Maryland State Conference NAACP. "That's not good."