DES MOINES, Iowa (AP) — Iowa's Republican governor on Wednesday called on President Donald Trump and his administration to preserve a federal program mandating that biofuels such as corn-based ethanol be blended into gasoline and diesel following a proposal from the Environmental Protection Agency to lower production targets for renewable fuels.

Gov. Kim Reynolds highlighted the issue amid a proposal by the EPA to lower production targets for biofuels in the so-called Renewable Fuel Standard program, known as RFS. She elevated her concerns by speaking at a press conference alongside RFS supporters such as farmers.

Reynolds, a staunch supporter of Trump, said she spoke with the president ahead of her remarks at an agriculture cooperative in Pella, about an hour southeast of Des Moines. She said that she also had a phone conversation with EPA Administrator Scott Pruitt.

"Both of them personally affirmed to me their continued commitment to the renewable fuel standard," she told reporters.

White House press secretary Sarah Huckabee Sanders confirmed Trump's call during a briefing in Washington but said "no definitive decision was made on RFS."

Reynolds' press secretary, Brenna Smith, said a decision can't be made until a public comment period on the plan ends Thursday.

The EPA oversees the decade-old RFS program, which sets how much corn-based ethanol and other renewable fuels must be blended into gasoline and diesel. The program is dear to politicians in agricultural states such as Iowa, the nation's largest producer of corn.

In addition to supporting farmers, the program is aimed at reducing dependence on foreign oil. Pruitt recently proposed targets for 2017 and 2018 set slightly below current levels, following a push by oil companies to ease the mandates.

Asked about Reynolds' call with Pruitt, an EPA spokesman said by email, "What Administrator Pruitt said in his confirmation hearing still stands: he doesn't want to take any steps to undermine the objectives in the statute of the RFS. We continue to work with RFS stakeholders to ensure EPA is applying the statute in a meaningful way, as Congress intended."

Trump gained early support in Iowa during his presidential campaign in part of emphasizing his support for the RFS program. It's a point U.S. Sen. Charles Grassley of Iowa pointed out after meeting with Pruitt on Tuesday.

"It's Administrator Pruitt's duty to follow congressional intent and also make good on President Trump's pledge to support biofuels," he said in a statement. "I'll oppose any effort to reduce blending levels or undermine the integrity of the RFS. I'm watching this issue closely and plan to hold the Administration accountable."

On Wednesday, a Senate committee delayed consideration of four of Trump's nominees for key EPA posts. U.S. Sen. Joni Ernst, also of Iowa, said in a statement she was not prepared to support the nomination of Bill Wehrum, Trump's choice to lead the EPA's Office of Air and Radiation. Wehrum, a lawyer in private practice whose clients have included pro-fossil fuel groups, would oversee the RFS program if confirmed.

"Holding the EPA's feet to the fire has put us on a path to receive strong reassurances on biofuel volumes and the EPA's commitment to follow both the letter and the spirit of the RFS," she said in a statement.

Reynolds' press conference comes days after she and the Republican governors of Kansas, Missouri and South Dakota sent a letter to Trump about the RFS. She said Wednesday that a reduction in biofuels production would hurt Iowa's economy. She plans to travel to Washington next week to drive the point home.

"They are feeling the pressure, and that's why we need to keep it up," she said.