Yes. You can use it as the subject of a sentence: "Republicans are divided in their feelings about their top candidates." That's how you know it's a noun--a word that names a person, place, or thing.
Richard Nixon was a member of the Republican Party.
Republican
republican
republican republican republican republican
republican republican republican republican
Republican
Is Harris Faulkner republican or democrat
Republican
republican
A republican is a member of the Republican Party.
Republican.
He is a Republican.