O.K. Industries, a poultry company in Arkansas upset about rising feed costs, said this was the first year since the company was founded during the Great Depression that it could not afford to give its employees a wage increase.

An agency spokesman said the E.P.A. can approve the request, deny it or take a middle path. The deadline is Thursday, but the agency says it needs more time to review public comments and formulate a decision.

The agency’s authority derives from a 2005 energy law that sets some of the most important ethanol quotas. The law says states can petition the agency for a reduction in the ethanol mandates on the grounds of severe harm to the economy or environment. Decisions must be made after consultation with the secretaries of energy and agriculture.

Ethanol is under siege from other quarters. Senator Kay Bailey Hutchison, Republican of Texas, has introduced legislation calling for a freeze of the mandate at the current level, saying it “is clearly causing unintended consequences on food prices.” The measure is co-sponsored by 11 other Republican senators, including John McCain, the presumptive presidential nominee.

The Federal Reserve chairman, Ben S. Bernanke, testified last week that “it would be helpful” to remove a 51-cent-a-gallon tariff on imported Brazilian ethanol. If Brazilian ethanol enters the United States market, domestic producers argue, the industry will suffer.

Image A mixture of yeast, enzymes and urea is poured into a batch of milo grain for fermenting into ethanol at the Reeve plant. Credit... Kevin Moloney for The New York Times

In a new report, the Organization for Economic Cooperation and Development is critical of biofuels, saying further development will raise food prices while doing little for energy security.