On Sunday, March 21st, the day that the House voted to pass health-care reform, Andrew Breitbart, the conservative Internet entrepreneur, was thousands of miles away, at home in Westwood, a neighborhood of Los Angeles. Breitbart, who in the past year has become a fixture on Fox News and a regular at Tea Party events, spends a lot of time on the road. In the preceding weeks, he had addressed the California Republican Spring Convention, in Santa Clara--"It's warfare to save the soul of the United States of America," he told the audience--and had introduced Sarah Palin at the National Tea Party Convention, in Nashville. But, the weekend of the historic vote, Breitbart, who has four young children, was fulfilling paternal obligations: taking the kids to watch the Los Angeles Marathon; having a ragtag group of little friends over to play.

These pleasant diversions did not, however, prevent Breitbart, who is forty-one, from posting frequently to his Twitter account, which he did in a manner that suggested he was in the midst of a hostile attack, or undergoing a psychotic break. "OhmyGod, the Dems are screaming the N word outside of my house. I swear. No, really. Trust me. It's true," he wrote just after 11 A.M.; four minutes later, he added, "Why are elected Democratic leaders in front of my house in LA standing lock-armed screaming racial epithets & homophobic slurs?" Four minutes later, he posted again: "Why is Steny Hoyer in Los Angeles sitting on Anthony Weiner's shoulders screaming the N word into my home? Weird."

These digital outbursts were prompted by Politico, which was reporting that several members of the Congressional Black Caucus--among them John Lewis, a hero of the civil-rights movement--had been subjected to racial slurs while walking through a crowd of Tea Party protesters in Washington; at the same event, Representative Barney Frank had allegedly been called "a gay epithet." On Twitter, Breitbart linked to the story, adding a condensed interpretation: "Dem strategy: Coordinated bloc walks in front of 'tea partiers' hoping to get youtube provocation to turn tables." Not long afterward, he posted again: "How's the Dems transparent, concerted attempt to provoke Tea Partiers going in this YouTube/FlipPhone environment? They got nada." The accusation of racist slurs, he suggested to his Twitter followers, who now number eighteen thousand, was no more plausible than was his own fictional harassment by Hoyer, the Majority Leader of the House, and Weiner, the Democratic congressman.

Breitbart is the founder of Breitbart.com, which, since 2005, has aggregated news from the Associated Press, Reuters, and other wire services. He is also the proprietor of several newer Web sites--Big Hollywood, Big Government, and Big Journalism--that provide right-leaning commentary and original reporting. Their content is largely supplied by unpaid bloggers, who are given a more prominent platform than they might otherwise attain. The Big sites are dedicated to countering what Breitbart believes is the leftist bias of American cultural and media institutions.

Breitbart's biggest scoop thus far has been a series of videos...