An economic advisor to Republican presidential nominee Donald Trump said reforming U.S. energy policy is a goal, but that a carbon tax is off the table.

“That is not a market-based way to have more energy benefits for the nation from our huge energy resources,” David Malpass told reporters in response to a question on whether a Trump administration could support putting a price on carbon. When further pressed on how Trump would address climate change, Malpass took a pass. “I can’t address that one,” he said, while indicating “sweeping” energy legislation is a “top priority.”

Malpass is the president of Encima Global LLC, an economic consulting company. He previously worked for Presidents Ronald Reagan and George H.W. Bush and also lost a bid for a senate seat.