Josh Haner/The New York Times
Mike Berland, a political operative who worked on Mrs. Clinton’s 2008 presidential campaign and is chief executive of Edelman Berland, calls it the “Wall of Trump.”
“We’ve never seen this before in politics,” Mr. Berland said. “This is not just a rally that happens once in a while. This is a continuous Trump rally that happens on Twitter at all hours. He fills the Twitter stadium every day.”