Iowa Republican Senator Charles Grassley is among the most vociferous. He's written letters to 13 Iowa companies that are members of the Grocery Manufacturers Association (GMA), a trade association lobbying for changes in the RFS, which has hired a public relations firm for their campaign. Grassley refers to GMA as the "Big Food" lobby. His letter states in part: "This smear campaign led by an organization of which you are listed as a member is harmful to an honest discussion and should be abandoned."

As for his contribution to intellectually honest and constructive discussion, Grassley was quoted by reporter Philip Brasher in the Des Moines Register saying: "If part of our problem is that the Chinese are going to eat meat and you've got to have corn and soybeans to feed the Chinese their meat, then why isn't it just as legitimate for the Chinese to go back and eat rice as it is for us to change our policy on corn to ethanol?"