Washington (CNN) Iowa Republican Sen. Joni Ernst on Tuesday called Environmental Protection Agency Administrator Scott Pruitt "as swampy as you get" for "transgressions" during his time leading the federal agency.

Ernst, who supported Pruitt's nomination, called a biofuel mandate agreement negotiated by the White House a "bad deal" during an S&P Global Platts Energy Podium event in Washington, D.C., and said the EPA's increased distribution of hardship waivers of the Renewable Fuel Standard diminishes biofuel demand.

"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.' But that's up to the President to make that call. I will remain highly critical of Administrator Pruitt," she said

She added that "a number of other transgressions" related to his alleged misuse of agency funds to show "he is about as swampy as you get here in Washington, D.C."

Pruitt currently faces about a dozen inquiries related to his actions leading the EPA. The probes are reviewing his travel expenses, personal security and other allegations of ethical concerns, such as Pruitt's below-market-rate lease with a lobbyist couple, one of whom represented a client before the EPA.

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