Environmental Protection Agency Administrator Scott Pruitt is facing the wrath of the ethanol lobby after proposing a plan that scales back the renewable fuel standard.

American Future Fund — a nonprofit group that self-identifies as conservative and pro free-market — released an attack against Pruitt, criticizing him for various controversies and calling on President Donald Trump to remove him from office.

“EPA Administrator Scott Pruitt is embarrassing President Trump,” the 30-second ad began, going on to list several scandals that have plagued the Republican’s tenure in recent months. “For the good of the country, Pruitt must go.”

Invoking Trump’s honor, the commercial at first glance appears to be solely a conservative-led attack on Pruitt. American Future Fund was formed to “provide Americans with a conservative and free market viewpoint to have a mechanism to communicate and advocate on the issues that most interest and concern them,” according to its website.

However, this 501(c)(4) dark-money group also boasts deep connections to the ethanol industry.

AFF is based in Iowa, a corn-rich state heavily invested in ethanol production. The organization, founded in 2008, received its seed money from Bruce Rastetter, the CEO of one of the largest ethanol businesses in the U.S., Hawkeye Energy Holdings. Nick Ryan — who has lobbied for Hawkeye and other Rastetter-led companies in the past — is AFF’s founder. The first annual Iowa Agriculture Summit in 2015 was put on by Rastetter and organized by Concordia Group, a consulting firm based in Des Moines. Additionally, Concordia is run by Ryan, and three of its staffers serve as officers at AFF.

The attack ad comes after Pruitt proposed modifications to the renewable fuel standard, a rule that requires oil refineries to use a certain amount of biofuels.

The debate over the renewable fuel standard has beset the Trump administration. Groups at odds over the 2005 mandate are two of the president’s biggest bases of support: oil producers in Pennsylvania and corn growers in Iowa. The rule is opposed by oil refineries that argue it’s killing their business. Corn farmers, however, support the mandate because it boosts demand for their product.

Sens. Chuck Grassley and Joni Ernst, both Republicans from Iowa, have also hit Pruitt for his stance against the biofuels mandate.

“I am hopeful that the president will just recognize that Mr. Pruitt is breaking our president’s promises to farmers and at some point he will say, ‘It’s time for you to go,’” Ernst stated earlier this month. “But that’s up to the president to make that call. I will remain highly critical of Administrator Pruitt.”

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This article originally appeared in The Daily Caller