When Barack Obama traveled to Texas this month to talk immigration, David Plouffe, his top message guru, decided to stay home and watch Twitter instead. While Obama spoke, Plouffe sat before two flat-screen televisions in the White House complex. One showed live footage of Obama in El Paso. The other flickered with a lightning-quick vertical ticker tape of people tweeting with the #immigration hashtag, reacting line by line to the President in real time. "I find it useful," Plouffe says, "to see what's penetrating."