Over a decade ago, Republicans invented the use of the word "Democrat" as an adjective, as in "Democrat Senator" or "Democrat bill". They did this because it rhymed with "bureaucrat", and I'm sure they liked the fact that it ended in "rat". All of which means that thinking progressives and liberals should never use this construction, but instead should use correct English and use "Democrat" only as a noun. If you catch yourself using "Democrat" like a Republican, you're only making them happy.
To sum up:
"Democrat" is a noun.
"Democratic" is an adjective.
"Republican" is an idiot.