WASHINGTON (CNN) -- Sen. John McCain Monday joined other GOP senators urging environmental regulators to ease rules demanding a sharp increase in ethanol use to help head off further increases in food prices.
Some GOP senators want regulators to roll back ethanol rules because of higher food costs.
The energy bill that passed Congress with bipartisan support in 2007 requires U.S. fuel marketers to increase the use of biofuels fivefold by 2022.
But McCain, the presumed Republican presidential nominee, and 23 other Republicans, including many who supported the bill, called on the Environmental Protection Agency to waive or roll back the law's requirements in order to ease pressure on food and livestock feed prices.
"Although many factors may contribute to high food costs, food-to-fuel mandates are the only factors that can be reconsidered in light of current circumstances," they wrote. "American families are feeling the strain of these food-to-fuel mandates in the grocery aisle and are growing concerned about the emerging environmental concerns of growing corn-based ethanol."
McCain did not vote on the energy bill, which passed the Senate on an 86-8 vote. President Bush signed the bill in December, hailing the biofuel mandate as "an important part of this legislation."
The drive to substitute cleaner-burning, domestically produced ethanol for gasoline has contributed to an increase in the price of corn -- both for human consumption and for livestock feed.
But bad weather that has damaged overseas grain harvests and the increased price of motor fuel have also contributed to rising food costs, witnesses told a congressional hearing on the issue last week.
The increases have become a global problem, with food riots reported this year in Egypt, Haiti, Yemen, Bangladesh and other nations. The United Nations formed a task force to deal with the problem last week.
The GOP senators, citing U.S. Department of Agriculture figures, said up to 30 percent of the U.S. corn crop could be diverted to fuel production this year. One of those who opposed the bill -- and a co-signer of Monday's letter -- said the ethanol mandates are now widely considered a "policy blunder" that Congress should roll back.
"People are now starving to death because of this transfer from food to fuel," said Sen. James Inhofe, R-Oklahoma, the ranking Republican on the Senate Environment and Public Works Committee.
But at the White House, presidential spokesman Scott Stanzel said biofuel requirements have only a "small impact" -- about 1.5 percent of the increase in food prices.
"We also think that the impact of that biofuel production will diminish over time, because, obviously, we've had weather-related issues around the world that had a huge impact on this," he said. E-mail to a friend