Feinstein in a statement said ethanol is the only part of the energy sector protected by what she said was a "triple crown" of government regulation -- its use is required by law, protected by tariffs and the U.S. government pays companies to use the fuel product.
The senators said the bill would eliminate about $6 billion in spending per year.
Coburn described the protection as "bad economic policy, bad energy policy and bad environmental policy" at a time when U.S. consumers are paying record-high prices for gasoline.
Industry backers said the tax credits encourage domestic energy production.
"The ethanol tariff makes our nation more dependent on foreign oil by increasing the price of imported ethanol," countered Feinstein.