No, not that one. This one. It's great to see that progressive insurgent Donna Edwards easily rode over hackish incumbent Al Wynn to capture the Democratic nomination for a safe Congressional seat in Maryland's 4th District. Her victory was by no means assured, as Terry Samuels pointed out, "Wynn has the support of House Speaker Nancy Pelosi and House Majority Leader Steny Hoyer as well as the endorsements of NARAL and the AFL-CIO; Edwards has the backing of the maverick Service Employees International Union and the liberal blogosphere, including Daily Kos founder Markos Moulitsas Zúniga." And the mavericks won. Wynn voted for the Bankruptcy Bill, for the war, for the repeal of the estate tax, and for the president's tax cuts. And though he had more money, these politicians, and his deep closeness to corporate America, doomed him, and did so publicly. And that last is important. As Matt correctly says, "the tree of progressive politics must be watered with the metaphorical blood of sellouts ever now and again. Some people seem to me to walk around in their head with a model in which politicians are very principled ideologues who then divert from their default status due to electoral fears. In a more plausible schematic, they have a natural tendency to drift in the direction of utter corruption and only electoral fear keeps them doing their jobs in a somewhat responsible manner." Wynn's loss will help power that fear for years to come. Primaries are the countervailing power that progressive activists can exert against corporate influence, and it's a deeply healthy development that the Left has begun using them successfully.