Actually, IMO, the primary source/secondary source distinction made in the OP is a rather arbitrary one in cases like this.
The Federalist Papers are a primary source for the study of American politics. One could easily say the same thing about many of the works suggested here—Tocqueville, Thoreau, Lippmann, Dewey, Beard, Hayek, etc., etc.
The thing is, many texts in political and intellectual history work as both primary and secondary sources. They are secondary sources in that they tell us about the events or people that the author is writing about, and they are primary sources in that they tell us about the types of ideas and attitudes that were circulating in American culture.
Beard’s text, for example, is a secondary source dealing with the political and economic interests that shaped the American Constitution, but it is also a primary source for any student interested in the early twentieth century rise of progressive history and politics.