"Indeed, it has always been those seeking wealth who were the source of corruption in government." -attributed to TJ
Corrupt government, how exactly? By running political ads in which the sponsor has to convince voters? Hardly an efficient method. Meanwhile, there was no such animal as a political ad in Jefferson's day. No, the time-honored ways to corrupt government -- which are what he had to be talking about -- are bribery, patronage, and legislated competitive advantages.
In other words, the ways that CONgress never seems to get around to addressing.
----------
They assume an authority which is nowhere so dangerous as in the hands of those who have folly and presumption enough to fancy themselves fit to exercise it. --Adam Smith