WASHINGTON – Federal officials today rejected Texas Gov. Rick Perry’s request to trim the country’s ethanol use, ruling that biofuel production is having a limited impact on food prices.

The decision marks the end of Mr. Perry’s challenge of energy-policy orthodoxy and is likely ethanol’s last test before a new Congress and president take office in 2009.

Announcing its decision, the U.S. Environmental Protection Agency said ethanol’s impact on rising corn prices, which have tripled over the past two years, is between 7 and 30 cents per bushel. The EPA ruled that it couldn’t trim the ethanol mandate because production hasn’t caused “severe harm to the economy,” even though rising corn prices have severely hurt Texas livestock producers.

“We acknowledge as part of our assessment that there is an increase because of biofuel production because of feed prices on certain industries,” EPA Administrator Stephen Johnson said. “However, is that the result of the [ethanol] mandate? Our answer is no.”

Mr. Perry declared himself “greatly disappointed” with the federal government’s decision, which was consistent with previous statements about the limited negative consequences of its ethanol policy.

“For the EPA to assert that this federal mandate is not affecting food prices not only goes against common sense, but every American’s grocery bill,” Mr. Perry said.

Mr. Perry requested the waiver in April, less than a year after Congress passed an energy bill that increased demand for biofuels. The law gave a big boost to corn-based ethanol, requiring the country to use 9 billion gallons in 2008 and 15 billion gallons by 2022.

The governor, whose state has few ethanol plants, said rising corn prices were hurting livestock producers and driving up grocery prices. He formed an alliance with a major Washington lobbying outfit, the Grocery Manufacturers Association, and pressed EPA to cut the 2008 mandate in half.

Politically, Mr. Perry appeared to have made his argument at the right time, even if the federal government disagreed. Many Republicans in Congress endorsed his request, as did Sen. John McCain, the Republican presidential candidate.

A number of experts, many of them overseas, have questioned the wisdom of continuing to subsidize corn-based ethanol. In July, the World Bank said that biofuel production pushed up global food prices by 75 percent.

But the experience also was marked by allegations that Mr. Perry simply gave voice to the complaints of wealthy Texas livestock producers upset with the rising price of corn, a feedstock for chickens and cattle. Many of those livestock interests are the governor’s biggest campaign contributors.

On Wednesday, Mr. Perry submitted additional comments to the EPA, which the agency didn’t consider because they arrived after the deadline for public comments.

Mr. Perry’s letter underscored his belief that ethanol production has increased the price of gasoline and diesel. Refiners would produce more gasoline, Mr. Perry argued, if they didn’t have to blend ethanol with conventional fuel.

That is the opposite argument offered by some experts who say ethanol has slightly suppressed gas prices. Ethanol is more than $1 per gallon cheaper than gasoline. Many refiners have another incentive to use it: they get a federal tax credit of 5.1 cents per gallon of E10 gasoline.

“It’s one of the main drivers for us -- to remain competitive in some areas,” said Judge Dobrient, senior vice president of wholesale marketing for Alon USA, a Dallas-based refiner.