The United States of America during its founding very much consciously modelled itself off the Roman Republic

It's also why America was founded as a republic not a democracy

Also the USA wanted to distanc itself culturally and politically from the great power of the time being Great Britain

Which is and was a non-codified constitution with parliamentary democracy and Britain's own brand of republicanism since the 13th century

If not a bit longer with the engrade ancient rides of the Anglo-Saxons which gives freedom