The message above from the National Republican Senatorial Committee is wrong on two counts:
First of all, the government shutdown is more the fault of Republicans than Democrats.
And second of all, the message ungrammatically uses the word “Democrat” as an adjective.
The name of the oldest political party in America is the Democratic Party of the United States. It’s members are known as “Democrats” (a noun).
Grammatically proper references to the party, its plans, its proposals, etc., require the use of the adjective “Democratic,” not the noun “Democrat.”
There is no such thing as “the Democrat Party,” or “Democrat leadership,” or ...