The ethanol lobby may have won this week’s political battle with President Donald Trump’s administration, but the war over the federal biofuel mandate is far from over.

The White House on Wednesday reportedly told Environmental Protection Agency (EPA) officials to stand down on making small changes to the Renewable Fuel Standard (RFS) after political backlash from corn states.

Midwestern GOP Senators held up Trump’s nominees for EPA positions until they were reassured no changes would be made to the RFS, that mandates refiners purchase ever-increasing amounts of ethanol.

Iowa Governor Kim Reynolds, a Republican, became involved as well, speaking to both Trump and EPA Administrator Scott Pruitt on Wednesday. Reynolds came away from the meeting reassured of the administration’s commitment to the RFS.

However, White House press secretary Sarah Huckabee Sanders said Trump “didn’t make any assurances on that specific issue.”

It was a power move, and it worked — for now.

“I don’t think this is over by any means,” Thomas Pyle, who served on Trump’s transition team, told The Daily Caller News Foundation.

“This definitely shows that Big Corn and biodiesel guys have a lot of pull with a handful of GOP Senators,” said Pyle, president of the free market Institute for Energy Research (IER).

A growing coalition of environmentalists, anti-hunger groups, the oil industry and conservative think tanks, including IER, have called for repeal or reform of the RFS, that they claim raises food and fuel prices.

EPA has been weighing several changes to the RFS, including allowing exported biodiesel to count towards meeting RFS requirements.

The RFS requires refiners to blend ever-increasing amounts of biofuel into the U.S. fuel supply. Most of that is met using corn-based ethanol.

Refiners that don’t blend fuel must purchase Renewable Identification Numbers, or RINs, to comply. Refiners have been agitating for reform or repeal of the RFS.

The changes, ethanol lobbyists argued, would benefit refiners who bear the cost of compliance with the RFS. The U.S. has had to import increasing amounts of biodiesel to comply with the ethanol mandate.

EPA also considered reducing the biodiesel quota 15 percent. EPA put out a request for public comment on the matter last month much to the chagrin of the biofuel industry.

“Our farmers and biofuels producers need greater certainty from the EPA,” lawmakers on the House Biofuels Caucus wrote in a letter Thursday to Pruitt.

“This proposition would upend infrastructure investments needed to blend ethanol into our fuel supply and pick winners and losers in a manner inconsistent with the Congressional intent of the Renewable Fuel Standard,” caucus members wrote.

It’s unclear whether the Trump administration’s promises to stay committed to the RFS will assuage corn belt lawmakers.

Iowa Sen. Joni Ernst, a Republican, said she would not support Trump’s EPA nominees until she gets “either in writing or a public announcement” of their support for the biofuel mandate.

“I am the single Iowa Republican on that committee — 11 to 10. Eleven Republicans, 10 Democrats. One vote makes a difference,” Ernst said.

This episode has only set the Trump administration up for further conflict with corn belt lawmakers.

“That’s a precedent for the administration going forward,” Pyle said.

“You can make changes to the RFS and still support the program, and that’s what Pruitt was trying to do,” Pyle said.

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This article originally appeared in The Daily Caller