Hours after saying he does not believe carbon dioxide is a “primary contributor” to climate change, the administrator of the Environmental Protection Agency said he doesn’t know whether the EPA has the legal right to regulate the pollutant.

Speaking to an energy industry gathering in Houston, Scott Pruitt said there is a “fundamental question” about whether his agency has the congressional authority to “deal with the CO2 issue,” The Wall Street Journal reported.

“It’s a question that needs to be asked and answered,” Pruitt said at CERAWeek.

{mosads}The statement indicates there could be a practical impact to Pruitt’s disbelief in the climate impact of carbon pollution, which is considered a major contributor to climate change by the vast majority of scientists.

During his confirmation hearing, Pruitt told senators he believes the EPA has an “obligation” to regulate carbon dioxide under a 2007 Supreme Court decision.

But Pruitt has also frequently discussed his desire to implement only activities that Congress has explicitly authorized the EPA to undertake.

During his time as Oklahoma’s attorney general, Pruitt sued against the 2009 “endangerment finding” the EPA released that concluded greenhouse gases harm public health and need to be regulated.

Trump has also panned the endangerment finding, opening up the possibility that the administration could undertake a review of the matter and attempt to undo the decision, which underpinned much of the EPA’s climate work during the Obama administration.