Reply #6: It's a Newt Gingrich construction...

[housewolf]

one of those right-wing "frames" to dis-empower the Democratic Party. The Republicans like to refer to themselves as "small d democrats" and they love to use the terms democracy and democrataic (as in process). By reframing the Democrats to the Democrat Party rather than the Democratic Party, they create separation between the big-D Party and other words related to democratic, democracy, etc.

That's one objection to the use of the term, the fact that it's something the Repubs try to impose on our language.

Another objection is that it is terribly improper English. The word Democrat is a noun (as you noted), as all the other -crat words are. The word Democratic is an adjective. The two are not interchangable. The word "Republican" is both a noun and an adjective so it can be used interchangably.