In Monday’s White House press conference with Senate Majority Leader Mitch McConnell, President Donald Trump swiped at Senate Minority Leader Chuck Schumer over the issue of nominations.

Trump said of Democrats, “They’re holding up every single nomination. Schumer and the group are holding up every single nomination. They’re obstructing — I’m telling you they’re not good politicians, but they’re very good at obstruction.”

The comment echoes a key talking point of McConnell, but in the case of one big nomination pushed by the President, it’s not quite right. In fact, it looks like Sen. Chuck Grassley and Sen. Joni Ernst, with the backing of the ethanol industry, are the ones doing the blocking.

According to Politico, in an account independently verified by energy industry sources, Ernst has refused to commit to supporting EPA air office nominee Bill Wehrum because EPA Administrator Scott Pruitt has recently proposed regulatory moves that have angered the ethanol industry:

But Ernst, who like Fischer had said earlier on Tuesday the meeting would determine whether she would support Wehrum to run EPA’s air office, which oversees the RFS, appeared skeptical about Pruitt’s support for biofuels, and she would not commit to supporting the nominee.

“Administrator Pruitt again claimed today that he will not do anything to undermine the program. However, we have heard this before. We now need to see it,” she said in a statement.

Ernst’s holdout status is a problem because Republicans have a razor-thin, one-vote majority on the Senate Environment and Public Works Committee—and Ernst is a member of it, meaning that as it stands, Wehrum’s nomination cannot proceed unless Pruitt or Ernst caves.

Sources say Ernst’s opposition, and the consequent inability of the Environment and Public Works Committee to pass Wehrum’s nomination out for consideration by the wider Senate, is the reason that today’s committee meeting– at which the issue of nominations was to be addressed– was “postponed.”

Grassley, who does not sit on the Committee, but does chair the Senate Judiciary Committee where he has significant latitude to block or advance judicial nominations and conduct oversight of the administration, appears to be backing up Ernst. According to the Des Moines Register, Grassley is threatening a hold on EPA nominees unless Pruitt caves on cronyist, pro-ethanol policies:

Asked what leverage he had to get Pruitt to do what he wanted, the veteran senator immediately replied: “Hold up EPA nominees. I think there’s plenty of senators would do that.”

It is rumored that Grassley has expressed openness to even more hardball tactics leveraging his Judiciary Committee position and “oversight” capacity to force the administration’s hand on biofuels-related policy.

Grassley and Ernst are seeking a reversal of EPA’s proposal to reduce biomass biodiesel quotas for next year and the year after, and to allow the use of RINs, or biofuel credits, from exported ethanol. Translated into English, that means the Iowa senators are irritated about regulatory moves that would weaken federal government imposed mandates designed to boost the biofuels industry.

Grassley and Ernst contend that ahead of the Iowa caucuses last year, Trump pledged his support for strongly pro-ethanol policy, and that he needs to adhere to it. However, Trump’s support for the Renewable Fuel Standard, colloquially known as the ethanol mandate, did not deliver him a caucus win—the first-place finisher in Iowa was in fact Sen. Ted Cruz, a staunch opponent of ethanol mandates and federal government programs designed to boost its production and consumption.

Trump’s takeaway from the Iowa caucuses may be that ethanol is not as important to the state as its senators are making out, or that he does not owe the ethanol lobby anything given his loss there.

Either way, it appears that Ernst, and potentially Grassley, are willing to play nominations hardball in order to secure a win for a big, home-state industry: Big Corn.

UPDATE: It looks like Ernst and Grassley’s obstructionism regarding Wehrum worked. The Daily Caller is reporting that the White House has intervened to force EPA’s hand. Notch another victory for hardball Senate tactics, and Big Corn.