WASHINGTON — As he traveled about his home state of Iowa recently, Sen. Chuck Grassley says he got a surprise phone call from President Donald Trump dismissing rumors his support had withered for corn-based ethanol.

Grassley quoted the president as stating: “When I was campaigning I said I was for ethanol. I want the people of Iowa to know I’m still for ethanol, and I want you to tell them.”

But less than a month after the Aug. 30 call, Grassley, farmers and biofuel industry interests who supported Trump say they feel betrayed by the administration’s apparent siding this week with the rival oil industry on the debate over government support for alternative fuels.

The Environmental Protection Agency, repeatedly citing the concerns of big oil, signaled this week it is considering lowering the amount of ethanol and other renewable fuels required in transportation fuels and heating oil.

Critics said the policy change would harm agricultural communities by reducing the demand for soy, corn and other crops used in alternative fuels. Indeed, soybean prices dropped the day after EPA’s announcement.

“There’s going to be a very, very strong backlash” should the administration follow through on lowing the requirements for alternative fuels, warned Monte Shaw, executive director of the Iowa Renewable Fuels Association.

“The heartland is what put him (Trump) over the top in the election,” said Shaw. “We’d be very disappointed if the first action the administration takes affecting the heartland is this.”

Congress mandated in 2007 that U.S. fuel blenders use 36 billion gallons of biofuels, including corn ethanol and cellulosic biofuel, by 2022. But it also authorized the EPA to alter the specific volume requirements if they would damage the nation’s economy.

Opponents of the mandate, including the oil industry, object to the law on the basis blended fuels are less efficient than pure fuels, and end up costing consumers more money at the pump and also in higher food prices due to the diversion of corn and other crops used in alternative fuels.

The intent of the law was to reduce dependence on imported oil and bring about greater energy independence in the U.S.

For the moment, Shaw and other biofuel advocates are giving Trump the benefit of the doubt by directing their ire at EPA Administrator Scott Pruitt, the former attorney general of oil-rich Oklahoma. They accuse him of unilaterally moving away from the president’s promise to support the government’s Renewable Fuel Standards of ethanol blend.

The White House did not return a request for comment. EPA spokesman Michael Abboud said only that the “EPA is currently seeking input from all stakeholders involved. Nothing has been finalized at this time.”

“I don’t know if we have a rogue (EPA) administrator or an administration that’s really changing course,” said Donnell Rehagen, chief executive officer of the industry Biodiesel Board, in an interview this week.

Bob Dinneen, CEO of the Renewable Fuels Association, put it this way in a separate interview: “The cynic in me would suggest the administrator of the EPA, from Oklahoma, is catering to the interests of the oil industry, which has never liked the renewable fuel standard, and always wanted to repeal it in some fashion.”

Republican Grassley, in a call with Iowa reporters this week, said Pruitt is “going off program and it is the president’s program. He’s doing an injustice to the president.”

Iowa’s other GOP senator, Joni Ernst, reached out to Trump to remind him of his promise made during the campaign and afterwards.

“It is also my hope that your EPA has not forgotten about the pledges that were made to my constituents and to farmers across the country,” she said. “And it is my hope that your support of American jobs and made in America energy has not wavered.”

Iowa is a primary producer of corn-based ethanol, a significant economic driver in the farm state ever since it was first produced and blended into gasoline in the late 1970s.

Sen. Joe Donnelly, D-Ind., joined in criticism of the potential policy change Friday.

“The EPA’s move towards undercutting biofuels is short-sighted and totally misses the mark,” he said in a statement. “At a time of international tumult, we should be supporting this renewable, American energy, not undermining it.”

But Rep. Pete Olson, R-Tex., vice chairman of the House Energy Subcommittee, and other oil state legislators have long criticized federal requirements on the use of renewable fuels.

An Olson spokeswoman did not return requests for comments this week. But he has called for repealing the biofuels law, saying it drives up the price of soybeans, corn and other foods.

A spokeswoman for the American Petroleum Institute, an industry group representing oil refineries, pointed to the organization’s previous position: that mandated increased use of biofuels harms consumers.

While ethanol makes up about 10 percent of the gasoline sold at the pumps, the institute said the requirement to use more biofuels would eventually raise the percentage of ethanol in gas to levels that would damage engines.

API and another oil industry group, the American Fuel and Petroleum Manufacturers, argued in letters to the EPA that rising biofuel prices would hurt the nation’s economy. Prices have been rising and could increase further, they said, if potential trade sanctions reduce biofuel imports from Argentina and Indonesia.

The EPA cited the argument in asking for public input on reducing the renewable fuel requirement.

But the Biofuel Board’s Rehagen said increasing renewable fuels “is exactly what Trump says he’s all about. America first, energy security, jobs at our biodiesel plans.”

He added: “If the primary mission of the administration is to help the oil industry, this is a great move, but I don’t think it’s the primary wish of most Americans.”

Contact Washington reporter Kery Murakami at kmurakami@cnhi.com.