Klein worked on Howard Dean's primary campaign in Vermont in 2003 and interned for the "Washington Monthly" in Washington, D.C., in 2004. "The media is as effective and important an agent for change as the legislative bodies, and I think it's where I'm happiest and most effective," Klein said. In 2003, he and Markos Moulitsas were two of the earliest bloggers to report from a political convention, that of the California State Democratic Party. In 2006, Klein was one of several writers pseudonymously flamed by "The New Republic" writer Lee Siegel (posting as a sock puppet called "sprezzatura").