Bill Lapp, president of Advanced Economic Solutions, said U.S. food inflation would reach 4.5 percent next year, adding about $30 billion to domestic costs.

"Globally it's a much more direct impact, a more immediate impact," he said. "A greater deal of the food consumption is done without further processing so you can have a much more dramatic impact in global prices. That's what's compelling the United Nations to ask for some relief on the biofuel mandates."

Under the five-year-old Renewable Fuel Standard, U.S. fuel companies are required to ensure that 9 percent of their gasoline pools are made up of ethanol this year, which means converting some 40 percent of the corn crop into the biofuel.

A White House spokesman said President Barack Obama was "looking at" the possibility of a waiver together with the Environmental Protection Agency and the USDA.

But with staunch farm belt support and an election looming, many political analysts say the odds of a waiver are low.