"Democrat Party is an epithet for the Democratic Party in the United States, used in a disparaging fashion by the party's opponents. While historical and occasional current usage includes non-hostile appearances, the term has grown in its negative use since the 1940s, in particular by members of the Republican Party—in party platforms, partisan speeches, and press releases—as well as by conservative commentators."
Again it doesn't seem like much of an insult. Seems republicans suck at insults.