I hate to be disagreeable (since I basically agree with you), but I think it's more reasonable in politics to take everyone (i.e., the Dems) at face value, in terms of their goals, and then decide what to label them by some empirical measure of these goals. In many cases -- perhaps half of Democrats -- their goals are, I think, suitable for calling them "socialist," but not "communist."
I would point out that my terminology comes from two, I think quite defensible, angles:
1) Empirically, or objectively, the best definition of "socialist" I can come up with would include those people who want to markedly increase the portion of a nation's GDP that is routed through government, especially when that portion is approaching a majority of an economy. (The US is currently at about 35%; most of Western Europe is 50% or slightly higher. Note that schemes to socialize health care, which would probably be favored by half of Democratic politicians, but very few Republicans, would increase the U.S. to a European level of government spending.)
2) Historically, even if you listened to, say, Radio Moscow in the early 1980s (I had a short wave), their terminology was that they were "socialist" countries, not "communist" countries, even though they were ruled by "communist" parties. It's not that they were trying to waffle away from the charge of being communist. It's that "communism" was the name for the end-goal of the party, the situation in the utopian "withering away of the state" predicted so falsely by Marx. And they had no pretentions of reaching that goal (they would have to give up their cushy Party/Government jobs).