An assistant to Rick Perry said Friday that the outgoing Energy Secretary won’t comply with a subpoena from the House of Representatives as part of its impeachment inquiry into President Donald Trump.

In a letter to the three House Democrats who issued the subpoena last week, Assistant Secretary of Energy Melissa Burnison said the Energy Department is “unable to comply with your request for documents and communications at this time” and argued that items requested “are potentially protected by executive privilege” and thus require careful review before they can be shared.

“Given that your inquiry lacks any legitimate constitutional foundation, any pretense of fairness, or even the most elementary due process protections, the Executive Branch cannot be expected to participate in it,” the letter said.