The “hinge moment” in Klein’s professional development came in April 2005, when, while still hurrying through his UCLA degree in political science, he mentioned on his blog a new healthcare report by the lefty think tank Center for American Progress. “I remember reading the comments, and seeing a lot of people arguing about Canada,” he recalls. “And I thought, Okay, I don’t know anything about the Canadian healthcare system, or any of these healthcare systems. So I told my readers I was going to do this feature for a week called The Health of Nations.” After checking out a bunch of books at a UCLA library, Klein launched a daily stream that summarized health-delivery systems in Japan, Canada, Germany, England, and France. “I mean, they were like Wikipedia entries or something,” he says. “But I loved it! I really thought it was interesting. And the readership really liked it, too. It was useful information, which was not really something that I was providing for them before. That’s when the sort of thing I like to write about began to take shape.”

The timing couldn’t have been better. Not only had Klein entered political blogging at a moment when digital natives were beginning to reconstitute the opinion-journalism profession, but the topic that fused his passion and wonkery—healthcare—was surging back into the public discussion, as progressive ideas resurfaced within American liberalism.

In 2005, just before graduating from UCLA, Klein was hired as a writing fellow at The American Prospect, which was co-founded in 1990 by Robert Kuttner, Robert Reich, and Paul Starr as a sort of exploration of modern Democratic progressivism through the lens of Washington policymaking. Klein says he knew he had found a home when his first real story meeting ended with then-editor Michael Tomasky telling him to go spelunking among the social scientists to figure out “what’s hot” in poverty. “Being at that place where policy journalism was the thing you did was absolutely critical for me,” he says. “Nobody said, ‘That’s too boring.’”

At the Prospect, Klein wrote about procedural Washington reform, tangled with the “ruthlessly serious” liberal hawks at The New Republic, and continued his path-clearing work in the weeds of healthcare delivery systems. His byline started popping up elsewhere, mixing pedagogy with policy prescriptions. “Think money drives medicine? You don’t know the half of it,” he wrote in The Washington Monthly. For Slate, he debunked “The Medical Malpractice Myth.” In the LA Times he advocated “Going Universal.”

In November 2006, a feistier and more economically progressive Democratic Party re-took the House of Representatives, most statehouses, and the US Senate from the gop. Pundits started declaring the death of “neoliberalism,” that strain of liberal commentary first championed at Charles Peters’s Washington Monthly in the early 1970s, in which the primary target was well-intentioned Democratic governance that had gone wrong in practice.

The Village was becoming a friendlier place, not just to the type of return-to-form liberalism Klein preferred, but to the emerging blogger-journalist hybrid he represented. At the beginning of the decade, only a couple of opinion magazines had blogs; by the end, nearly all did. In March 2008, The New York Times took notice of all these Beltway blogger kids, profiling not just one but three DC blogger houses, with such wince-inducing details as an Iron Chef-style cooking contest between Team Liberal (including Klein) and Team Libertarian, duly broadcast on BloggingHeads.tv.

But not everyone was a fan. Washington Times writer Eli Lake dubbed the whole crowd “the Juicebox Mafia.” Blogger Mickey Kaus accused Klein at various points of “hectoring naïveté” and “spout[ing] the party line,” and I once mocked Klein on Reason.com as an “omniscient child pundit.”