Today, U.S. Sen. David Vitter (R-La.), top Republican on the Environment and Public Works Committee, sent a letter to Janet McCabe, nominee to be Administrator of the U.S. Environmental Protection Agency's (EPA) Office of Air and Radiation (OAR). The letter reiterates questions from their exchange at her nomination hearing Tuesday, April 8, including her specific role in the Interagency Working Group that was tasked with developing the social cost of carbon estimates, as well as the role of those in the Office of Air and Radiation.

"The EPA seems to go to great lengths to keep this information hidden from the public, but if Ms. McCabe wants Senate approval, there is absolutely no reason she can't answer these very simple questions," Vitter said. "The social cost of carbon estimates are used frequently to justify costly and controversial regulations, and the participants involved in developing the estimates have been kept completely anonymous."

During McCabe's nomination hearing this week, she denied involvement in the Interagency Working Group. Click here to watch her exchange with Sen. Vitter.

Vitter has been critical of the development of these estimates throughout the process, highlighting the lack of transparency and requesting information on who was involved with the Administration's hand-selected Interagency Working Group. Click here to read more.

Click here to read today's letter.