“This time the energy is being fueled by a lot of forces that did not exist back then,” said Christopher Ruddy, chief executive of Newsmax, the conservative magazine, Web site and publisher. Its “ObamaCare Survival Guide,” a New York Times best seller, has sold a half-million copies, he said.

“There’s this new conservative media constellation, and that’s playing into this,” he said…

Democrats usually get more credit for their social media expertise, thanks in large part to the successful tactics of Mr. Obama’s 2008 and 2012 campaigns. But conservatives’ use of blogs and, increasingly, Twitter to drive their messages and spur online protests have been a major factor in Mr. Cruz’s movement.

Few Republicans have been more savvy about the media game than Mr. Cruz, who hit the phones almost immediately after his 21-hour marathon speech ended Wednesday. One of his first calls was to Rush Limbaugh’s radio program. Glenn Beck would come later, as would a conference call with conservative bloggers. There were two Fox News interviews.