Sen. Joni Ernst Joni Kay ErnstThe Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting Liberal super PAC launches ads targeting vulnerable GOP senators over SCOTUS fight Romney backs pre-election Supreme Court vote, paving way for McConnell, Trump MORE (R-Iowa) slammed Environmental Protection Agency (EPA) head Scott Pruitt Edward (Scott) Scott PruittJuan Williams: Swamp creature at the White House Science protections must be enforceable Conspicuous by their absence from the Republican Convention MORE Tuesday, calling him “about as swampy as you get.”

“He is about as swampy as you get here in Washington, D.C., and if the president wants to drain the swamp, he needs to take a look at his own Cabinet,” Ernst said at an event organized by Platts, according to Bloomberg News.

The sharp rebuke from a member of President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE’s own party was in response to Pruitt’s ethical and spending scandals, such as renting a condo from the wife of an energy lobbyist for $50 for each night he spent there, and lavish taxpayer spending on security and other costs.

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Ernst’s criticism is fueled, at least in part, by her frustrations over Pruitt’s handling of the federal ethanol mandate under the Renewable Fuel Standard.

The Trump administration is due soon to release details of a slate of policies meant to ease the burden of compliance on fuel refiners, while also trying to give some help to the ethanol industry.

The plan is expected to include allowing exported ethanol to count toward the mandate — effectively reducing the mandated volume — while allowing higher ethanol blends to be sold in the summer than are currently allowed.

Ernst and other ethanol supporters say the export provision, along with the EPA’s liberal use of its authority to waive the mandate for struggling refineries, is a betrayal of Trump’s promise to uphold the mandate.

“Mr. Pruitt is breaking our president’s promises to farmers,” Ernst said, according to Bloomberg, adding that Trump at some point may “say it’s time for you to go, but that is up to the president.”