Well this is very good thing. The Washington Post is one of the local papers in the race, so the dynamic is more local than national in this case.  

REP. ALBERT R. WYNN has represented Maryland's 4th Congressional District since 1993, and in that time he has never faced a serious challenger. This year, in Donna Edwards , he does. Ms. Edwards, a lawyer and foundation executive with a distinguished record of civic activism, is Mr. Wynn's opponent in the Sept. 12 Democratic primary. Tough, articulate and knowledgeable, she is one of the smartest and most impressive newcomers in Maryland politics.

The 4th District, comprising parts of Prince George's and Montgomery counties, is heavily Democratic, a profile that meshes with Ms. Edwards's long involvement in liberal causes. She has championed a higher minimum wage, campaign finance reform and an array of environmental issues, and she fought for legislation to curtail domestic violence. Locally, she was an ardent opponent of National Harbor, the multibillion-dollar development underway in Prince George's, but she came around to supporting it when she was satisfied that it would include a balance of commercial, entertainment and residential components. Her assent removed one of the project's last major hurdles -- a fact that testifies both to her skill as an advocate and her openness to reasonable compromise.

Now it's up to Donna's last minute media blitz, the field campaign, and free media that's going to come out as the primary gets noticed.  Donna Edwards, Ned Lamont, and Jennifer Lawless are part of a need breed of aggressive and progressive East Coast politician, accomplished non-candidates who are turning to politics as a vehicle for successful change.

I've written about Donna here, here, here, here, here, here, here, and here.  So MyDD readers have had a bit of a jump on her primary story.  Not being in the district, it's hard to tell how this will play out.  Movement progressives have already played a big role in shaking up the status quo in Connecticut; this is just confirmation that the winds of progressive change are growing to gale force.

Update: Let me spell out what this endorsement means. The biggest hurdle for any candidate is to appear 'viable'. Viability is an ephemeral quality, prone to spin and bullshit, but it's basically the idea that a candidate has a shot at winning a race. Political people want to spend their time and money on races that can be won, so a key challenge in politics is convincing enough donors and political influentials that a race is real and can be won. Once a candidate has become 'viable', money and support is unlocked by establishment groups whose primary interest is in not being embarrassed. The Washington Post endorsement means that Donna Edwards is now a real and viable challenger to Al Wynn. That's huge.