How Did the Political Structure in Rome influence U.S. Political Structure

I am inclined to believe that the political structure of the United States was influenced by the political structure in the Roman Empire. U.S. Senators are a testament to this. U.S. Senators in America are reminiscent of the senatorial Roman politicians who supplemented the office of Emperor.

The founding fathers, among others, were learned men and had a grounding in the classics, thus they were well aware of the ancient governmental systems of Rome and Greece as they were understood back then. Many people criticise the Roman system - and to be fair, it was never really conducted in the manner intended - but as an example of a civilisation that threw off the yoke of tyrannical kings in favour of representation and so forth, the Republican system had a lot to offer the Americans who were miffed at the lack of representation in England.

The problem here is a few retrojections of history. First that St. Augustine wrote his City of God over the manuscript of Cicero's Republic, considered the first constitution, a fact that wasn't discovered until the 19th century, after the US had been founded. In addition, with the Punic Wars, Roman history itself was rewritten to justify the imperialist conquest, against the laws of the Republic so the winners rewrote it for precedent: why most believe they didn't live up to their model, when in fact the generals no doubt did away with the republic after they couldn't get their agrarian laws past the Senate.

Had this not been, the Americans would have been aware that pillaging the land of the Natives and working it with plundered slaves was exactly the sort of thing Cicero was prohibiting in On Duties when he says a purpose of government is to protect property, saying that we own nothing except for long occupancy, and then goes on to talk about Arpinium, where he was from, was the last city let into the republic before the senators began plundering land (with a custom or decree, not law), implying instead they should protect the long standing rights of it's denizens.

The idea of classical modelling wasn't specific. As I said, the founding fathers were well acquainted with graeco-roman history as it was understood in the 18th century and simply took ideas from it to suit themselves. A slavish re-enactment of Roman politics was never going to be on the cards given the cultural differences and ambitiions of the colonies compared to the classical societies they were borrowing from.

The founding fathers of the US were interested by the concepts of "separation of powers"  and "checks and balances" between magistrates, senate and popular assemblies they saw in book VI of Polybius.