It is one thing to run a movement, filled with passion and an army of true believers set on a single goal, and another to run a country, where competing agendas are often fueled by deep divisions. And while the communications stars do seem to be aligned for Mr. Obama, historians, political scientists and strategists say that being the first Internet president poses its own challenges. The Internet, after all, is a two-way medium, and the bully pulpit is inherently one-way.

“I don’t think there’s any doubt that he will use nontraditional venues for taking his case to the people, and that’s all fine, but it’s still going to be a rough ride,” said George C. Edwards III, a political scientist at Texas A&M University and the author of “On Deaf Ears: The Limits of the Bully Pulpit.” “There’s a great myth out there about the bully pulpit. Presidents can rarely move public opinion, and that’s true across all presidents at all times.”

To begin with, it can be difficult to command attention; even F.D.R. had trouble. Despite the popular impression that Americans spent the Roosevelt era riveted to their radios, Mr. Edwards cites a poll in April 1939 that found 37 percent of the public had never listened to the fireside chats, 39 percent said they listened only sometimes, while 24 percent said they usually listened.