WHEN DISCUSSING Markos Moulitsas and the eponymous left wing blog that he runs, The Daily Kos, it's helpful to start with a few facts. The Daily Kos (rhymes with rose, based on Moulitsas' old army nickname) is far and away the most popular blog on the Internet: Kos averages over 400,000 page views a day. By comparison, the second most popular blog, right leaning law professor Glenn Reynolds's Instapundit, averages barely 200,000 page views a day.

Kos also walks a different beat than his conservative counterparts. Most popular conservative bloggers (like Instapundit, Power Line, and Roger Simon) use their blogs as a platform to discuss not only their political views but anything else that catches their fancy. For instance, Power Line might devote 500 words to celebrating Riche Haven's birthday or Reynolds might devote half an afternoon to digital photography or nanotechnology. While all of these gentleman are supporters of George W. Bush, none are activists--at least not on their blogs. The prototypical conservative blogger offers political commentary, but that's where his mission ends.

Kos outwardly and unambiguously defines his role differently. He has proudly assumed the task of getting Democrats elected and never denies that he is an activist, not an objective commentator. He has built the Daily Kos community to further that activism with painstaking care. And while Kos is certainly not the finest writer in the blogosphere, he is amongst its shrewdest operators. And by almost any measure, he is the most successful blogger in the business.

TEN MONTHS AGO Kos's ascendancy seemed hardly pre-ordained. On April 1, 2004, Kos responded to the savage murder of four American contractors in Falluja by writing, "I feel nothing over the death of the mercenaries [sic]. They are there to wage war for profit. Screw them."

At the time of this outburst, Kos was using his blog as a platform to create advertising revenue and to establish credibility for a political consulting business. His outburst threatened to destroy the budding project.

Immediately Kos' foils in the conservative blogosphere demanded that the politicians who advertised on Daily Kos remove their ads and disassociate themselves from both the site and its proprietor. One of the first to heed this call was Texas Democrat Martin Frost. His campaign noted its departure from Kos's site by saying, "There is no place for these disgusting remarks in this nation's discussion on foreign policy." Other campaigns followed the Frost campaign's lead and it seemed like Kos might have been in trouble.

But then something funny happened. While politicians distanced themselves from the site, Kos's fans stayed put. A quick glance at Kos's traffic figures for April of 2004 shows no drop-off in the wake of Moulitsas' controversial comments. And since the eyeballs remained, politicians soon returned. Political advertisers who had left were replaced in short order by other office seekers. At first it seemed the entire affair might ruin Kos; in the end it was, as he put it in an interview with the New York Times, nothing more than a "blip."