Until Iowa is not the first US primary, these corn producers will always have an an advantage in influencing American politics.

Well sure, but there are a lot of lobbying groups relying on the subsidies. Beef, pork, ethanol, corn syrup, international food exporters.

If a congressperson raises the price of the commodity they all rely on, they will piss of a LOT of money, and probably not raise enough next election cycle, and lose their seat.