Last election I was a bit surprised at the number of Democratic candidates for Congress who did their best to hide their party affiliation, or at least not advertise it very loudly. I can see the wisdom of the argument for doing this - it's the competitive districts you're focusing on and competitive districts require wooing independents and people from the other side. I'm not sure it's all that smart a strategy, and it's certainly a flawed strategy from the perspective of building the party brand over the longer term, but I can't say that it doesn't make sense in some districts.
However, with polls having Democrats up 9 points nationally maybe it's time to rethink?