Earlier this month, President-elect Donald Trump selected Oklahoma Attorney General Scott Pruitt as his nominee to head up the Environmental Protection Agency — an agency that Pruitt is also currently suing. Now, a group of six U.S. Senators has called on Pruitt to disclose his reported connections to the oil industry.

The senators — all members of the Senate Environment and Public Works Committee — sent Pruitt a letter [PDF] on Tuesday in advance of the upcoming confirmation hearing process.

“It has long been the expectation of this Committee that the EPA Administrator put the public’s interest first and commit to running the agency in a fully transparent manner,” reads the letter.

The senators say they are “troubled” by reports that, as Oklahoma AG, Pruitt used energy industry talking points “nearly verbatim” in his correspondence with the EPA about the levels of methane pollution in the state.

The letter also questions Pruitt’s “close relationship with Devon Energy,” the Oklahoma-based oil and gas company that, according to a 2014 New York Times investigation, actually drafted letters for Pruitt to send to the EPA, accusing the agency of exaggerating the amount of air pollution resulting from new natural gas wells in the state.

“What that conduct says about your ability to lead EPA in a manner that is not beholden to special or secret interests is a subject that we expect will receive a full airing during your confirmation hearing,” caution the senators. “Before the Senate votes to confirm you to run EPA, it is important that you provide a full disclosure of your relationship with the energy industry.”

Pruitt’s membership on the board of the Rule of Law Defense Fund is also a point of concern for the senators, who contend that the Fund has received substantial amounts of money from billionaire industrialists Charles and Bill Koch, vocal critics of EPA policy.

The senators want Pruitt to clarify his connections to the Fund, the organizations major expenditures, its donors, and to provide details on “all federal and state legislation or regulations the Fund has taken a position on.”

“The confirmation process… is an opportunity for you to dispel the notion that the advocacy you have undertaken on environmental issues as Attorney General of Oklahoma has been directed by and for the benefit of the energy industry,” concludes the letter, which was signed by Sen. Sheldon Whitehouse (RI), Sen. Ed Markey (MA), Sen. Jeff Merkley (OR), Sen. Cory Booker (NJ), Sen. Bernie Sanders (VT), and Sen. Ben Cardin (MD).

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