The original LEFT BLOGOSPHERE was notable not for being especially Lefty - other than on Iraq, I suppose, which coded you as a Lefty at the time - but instead for consistently arguing that blurring the differences between Republicans, instead of embracing them proudly, was ineffective loser stuff.
I don't think I've wavered much from that in all of those years.
One way that bipartisan mind virus infects DC Democrats is that it leads them to appoint and reappoint Republicans, or supposed nonpartisans (secret Republicans), to important jobs. Whatever else you can say about the left side of the Democratic coalition, they're less likely to argue that Republicans are Good, Akshually.