Sen. Tom Carper led his colleagues in calling for Environmental Protection Agency Administrator Scott Pruitt to address the apparent conflict of interest regarding his participation in EPA’s review of the Clean Power Plan, which Pruitt formerly challenged in court as Oklahoma’s attorney general.

Sens. Carper, D-Rhode Island; Richard Blumenthal, D-Connecticut; Cory Booker, D-New Jersey; Maria Cantwell, D-Washington; Dick Durbin, D-Illinois; Kamala Harris, D-California; Patrick Leahy, D-Vermont; Edward J. Markey, D-Massachusetts; Jeff Merkley, D-Oregon; and Sheldon Whitehouse, D-Rhode Island, requested information on Pruitt’s efforts to mitigate the likely conflicts of interest.

The senators wrote, “Beginning in August 2014, you filed actions in both the U.S. Circuit Court of Appeals for the District of Columbia — West Virginia v. EPA — and the Northern District of Oklahoma challenging the Clean Power Plan on behalf of the state of Oklahoma…We all continue to believe that you should have committed to recuse yourself extensively from a number of matters during your confirmation process. Nevertheless, your anticipation of, and preparation for, signing of the Federal Register notice and filing of the motion in the D.C. Circuit should have triggered the more limited recusal policy to which you have already and repeatedly agreed.”

Prior to his confirmation as EPA administrator, Pruitt said he would “seek authorization [from the EPA’s Designated Agency Ethics Officer] to participate personally and substantially in particular matters involving specific parties in which [he] know[s] the state of Oklahoma is a party or represents a party.”

In March, Carper led lawmakers in calling on Pruitt to address similar conflicts of interest regarding EPA’s review of the Clean Water Rule, which Pruitt also sought to overturn as Oklahoma’s attorney general. Pruitt has yet to respond to that March 21 request.