The first question that offers itself is, whether the general form and aspect of the government be strictly republican. It is evident that no other form would be reconcilable with the genius of the people of America; with the fundamental principles of the Revolution; or with that honorable determination which animates every votary of freedom, to rest all our political experiments on the capacity of mankind for self-government. If the plan of the convention, therefore, be found to depart from the republican character, its advocates must abandon it as no longer defensible.

Federalist No. 39 Full text at Wikisource. - Federalist Papers (1787–1788)