As food prices surge on grocery store shelves, Republican lawmakers on Tuesday said Congress should reverse course and slow a fivefold boost in biofuel use by 2022, or even drop entirely mandates to use ethanol blended from corn. Ethanol, once the darling of the United States' plan to wean itself from foreign energy, has come under attack in recent months as prices for commodities including corn and soybeans have risen to record highs, boosting retail prices for meats, vegetables and bread.