Via Larison, some interesting polling from GQR for NPR. They test some different Democratic and Republican messages head-to-head. And they do them two ways. In one round, each message starts "Democrats say..." or "Republicans say..." whereas a different batch of people get the message test with just "some people say..."
In all instances, the Democratic message beats the Republican message fairly badly. But identifying the Democratic message as "Democrats say..." uniformly results in a slight decrease in its popularity whereas identifying the Republican message as "Republicans say" slightly increases the message's popularity. I'm not 100 percent sure how to interpret that -- on the one hand, it speaks to some enduring strengths of the GOP brand, but on the other hand the Republican messages poor very poorly overall so their brand is hardly in good shape.