Yet Another Comparison of the Contemporary U.S. to Ancient Rome
The following quotes are from Politics and Vision, by Sheldon S. Wolin [Princeton Classics Addition]. They describe the transition in the role of politics in society from the Athens of Plato’s and Aristotle’s times through the Roman Republic to its replacement with autarchy. To be clear, Wolin wasn’t making the comparison I am making, but restricting his analysis to then and there.
According to Plato and Aristotle, “. . . the political association existed to serve the material and cultural needs of its members, and although power was necessary to direct and coordinate human activities in order that these needs could be best satisfied, it did not follow that power was the central mark of an association composed of contributing parts. When those considerations lost their compelling force, however [in the Roman Republic], the way lay open for considering power as the central political fact.“ [p.82]
“During the republican period, political activity took the form of group politics wherein rival oligarchies, drawn from largely the same social strata, competed for office, prestige, and power.” 
“Although the interplay between social structure and political institutions did not always function smoothly or effectively, it did useful service in keeping the political system sensitive to changing social pressures and it did help to direct political behavior along fairly orderly lines.” 
“. . . [The Romans] sensed that institutions function as a kind of common denominator of action, requiring the political actor to respect established conventions and settled expectations.” ]76]
As time went on, “. . . the citizen . . . came to be regarded less as a participant than as a subject . . . .” 
The larger point Wolin was making is that the citizens shared in that change in attitude; the functioning of the republic as a “contest of power” [from Michel Foucault] among oligarchies fomented such an attitude. That attitude existed in a reciprocal feedback relationship with the political process, growing in significance and contributing to the end of the republic.
In response to the demise of the republic, “. . . one impulse was to . . . seek refuge in a ‘golden age’ . . . . Another and far stronger impulse . . . was . . . to look towards the political regime for something over and above their material and intellectual needs, something akin to salvation.” 
Finally, “The fate of the body politic was resigned to . . . its governing head. He was the sole instrument of the divine logos [author’s italics], of that saving force which, by his mediation, could remediate society and its members . . . .“ 
I would say that in the history of the U.S. the period up to the Civil War represented the period of our political process being like that of ancient Athens (at least in areas of the country not dominated by plantations). Even though it was not a direct democracy, and citizenship was as limited as it was in Athens, the citizens did feel that they were ‘the sovereign’. After the Civil War the entire nation became like Wolin’s description of the Roman Republic. In Rome those “oligarchies” were composed of families; here there were initially individuals — plutocrats — the “Robber Barons” — in place of “oligarchies,” but true oligarchies of Wolin’s description emerged when industries competing for public favor replaced individuals in that role.
Are we currently witnessing our own transition to a post-republican era? The real key seems to me to be how many people are willing accept a status as “subjects.” To participate, however ineffectual one’s participation may seem to be, is to resist authoritarianism and to keep alive the hope that ‘the people’ can regain sovereignty, wresting ultimate political power from the oligarchies. Fans of President Trump seem to me to be already in ’post-republic mode’.