We don't have a Representative Republic.
We have a Constitutional Republic.
Ducks in a row...Representation is spelled out within the Constitution.
Congressional oaths are to the Constitution.
(...I will support and defend the Constitution of the United States...)
One must come before the other.
Sorry, but you're misinformed and very wrong on America's form of government.
I may have made that same error myself. So hard it to be perfect it but it's worth preserving the correct terms.
Are we a Constitutionally limited representative republic? Or just a Constitutional Republic? I'll assume the latter.