WASHINGTON — Midwestern senators welcomed signals Wednesday that the Trump administration would back off of proposals to weaken federal renewable fuel mandates, but the lawmakers weren’t ready to declare victory just yet.

“We want the president, we want the EPA, to be very public about the steps they can announce,” Sen. Joni Ernst, R-Iowa, told reporters.

Ernst was straightforward about her role in prompting the Senate Environment and Public Works Committee to cancel Wednesday’s vote on several Environmental Protection Agency nominees. Those nominees included Bill Wehrum, who has been tapped to head the office that administers the renewable fuel program. A member of the committee, Ernst said she found Wehrum’s answers “pretty darn squishy” when she pressed him on support for renewable fuels.

“I told them outright I would not support him if I didn’t have assurances,” she said, then noted that Republicans have a razor-thin 11-10 advantage on the panel. “One vote makes a difference.”

Political leaders and renewable fuel groups across the Midwest have criticized the EPA’s recent proposed volume requirements under the Renewable Fuel Standard — a policy that requires refiners and importers to blend a certain amount of ethanol, biodiesel and advanced alternatives into the nation’s fuel supply.

In particular, they have said the agency’s proposed biodiesel volumes are so low they could significantly harm the industry and cost jobs.

Another proposal to count exported fuels against the domestic requirements also has raised concerns.

Iowa and Nebraska represent the country’s two biggest ethanol states. All four GOP senators from Nebraska and Iowa attended a Tuesday meeting with EPA Administrator Scott Pruitt in the office of Sen. Chuck Grassley, R-Iowa.

Grassley described that meeting as an effort to persuade Pruitt to make good on the promises to support renewable fuels that President Donald Trump made to Iowans on the campaign trail.

Trump spoke to Iowa’s Republican Gov. Kim Reynolds by phone Wednesday in a conversation she described as “positive and productive.”

Wednesday also brought word that White House officials had directed the EPA to abandon both the reduction in biodiesel requirements and the separate proposal to allow exported renewable fuel to count toward domestic quotas, according to individuals familiar with the decision but not authorized to speak publicly about the move.

“A handful of senators completely cornmailed the administration by threatening to hold nominees hostage until they get their way,” Stephen Brown, the head of federal affairs for refiner Andeaver, said in an email. “Faced with tactics that would have made Don Corleone blush, the administration essentially had no choice but to relent.”

Still, pro-ethanol senators such as Grassley and Ernst aren’t satisfied. Ernst said they want something more definitive — and public — from those in charge.

Those negotiations represent a somewhat delicate dance given that the administration must follow established rule-making procedures that require the gathering of public input before releasing the final 2018 volume requirements at the end of next month.

And in the meantime, those nominees are cooling their heels.

“They are anxious to get this resolved,” Ernst said, referring to both the administration and Senate committee aides. “They are nonstop on the phone with my chief, with my staff.”

She declined to share specifics about the commitments she’s seeking from the administration, but she said the bottom line is that she wants to see administration officials do more than just follow the letter of the law.

They need to follow its spirit of supporting the renewable fuel industry, she said.

“We’re getting closer,” Ernst said.