At issue this week was the Renewable Fuel Standard, a program that requires refiners to blend an increasing amount of renewable fuels such as corn-based ethanol into traditional fuels such as gasoline.
On the campaign trail, then-candidate Trump vowed to protect the program, which is popular in the agricultural areas he mostly won over. But as a president championing fossil fuel development, Trump's EPA floated the idea of scaling back the program earlier this year.
On Thursday, the EPA decided to require refiners to blend 19.29 billion gallons of renewable fuels in 2018, up from 19.28 billion gallons this year. The agency slightly upped the requirement for advanced biofuels, but left the conventional biofuels requirement for 2018 and the biodiesel mandate for 2019 unchanged.
The Renewable Fuel Association, a biofuels industry group, said it was pleased EPA didn't scale back the levels, but argued the Renewable Fuel Standard needs to be a "forward-looking program" to drive investment in new technologies.
"The biofuels industry will rise or fall together, and thus we are disappointed the final rule is not more aggressive with regard to other advanced biofuels such as biodiesel," RFA President Bob Dinneen said in a statement.
Similarly, Iowa's senior Republican Sen. Chuck Grassley said he was glad that EPA dropped its earlier proposal, but had hoped for higher blending levels.
"The EPA's announced renewable volume obligations fall short of the full potential of the U.S. biofuels industry. That is disappointing," he said in a statement.
Grassley and Sen. Joni Ernst, the junior Republican from Iowa, were among several midwest lawmakers who threatened to hold up Trump's EPA nominees if he scaled back the Renewable Fuel Standard.