President Donald Trump said he is “not happy” with Secretary of Health and Human Services Tom Price, as revelations continue to emerge about his use of private planes for government travel.

“I will tell you, personally, I’m not happy about it,” Trump told reporters Wednesday outside the White House as he prepared to depart for a trip to Indiana.

“I’m going to look at it. I’m not happy about it, and I will let him know it,” Trump continued.

Asked if he will fire Price, Trump responded, “We’ll see.”

Price has taken as many as 24 private flights in the past few months, costing the government an estimated $300,000. The HHS Office of Inspector General said last week that it has opened an investigation into his travel.

Earlier Wednesday, the House Oversight Committee began its own inquiry into federal agency travel. Treasury Secretary Steve Mnuchin has also come under scrutiny for requesting a government plane to travel to his European honeymoon this summer. The request, which he said was in the interest of “national security,” was later withdrawn.

The committee sent a letter to Price asking that he “identify each usage of a private, non-commercial aircraft by a non-career official” by Oct. 10.