Washington (CNN) President Donald Trump's budget director and soon-to-be acting chief of staff, Mick Mulvaney, called Trump "a terrible human being" during a campaign debate in 2016.

In a video posted by The Daily Beast , Mulvaney said at the debate with his then-Democratic challenger for South Carolina's 5th Congressional District seat, Fran Person, that he was supporting Trump for president, albeit reluctantly.

"Yes, I'm supporting Donald Trump," the incumbent Republican, who later won reelection, says in the video. "I'm doing so as enthusiastically as I can, given the fact that I think he's a terrible human being, but the choice on the other side is just as bad."

During the transition, Trump tapped Mulvaney to be director of the White House Office of Management and Budget. On Friday, Trump also named him to take over as acting chief of staff at the end of the year after John Kelly leaves the administration.

"Mick has done an outstanding job while in the Administration," Trump wrote in a tweet Friday.

"I look forward to working with him in this new capacity as we continue to MAKE AMERICA GREAT AGAIN!" he added in a follow-up tweet . "John will be staying until the end of the year. He is a GREAT PATRIOT and I want to personally thank him for his service!"

The White House did not immediately respond to CNN's request for comment Saturday on Mulvaney's remarks in 2016.

An Office of Management and Budget spokeswoman, Meghan Burris, said in reaction to the video, "This is old news. These comments were made in 2016, when he was a Congressman and had yet to meet the President. Congressman Mulvaney continued to support then-Candidate Trump throughout the election, and his support for President Trump has never wavered while serving within the Administration."

Mulvaney "both likes and respects the President, and he likes working for him," Burris said in the statement. "More importantly, Director Mulvaney believes in the President -- because he is working every day to lift up millions of Americans and stands up for our great country."

The Herald newspaper in South Carolina reported Mulvaney's debate remarks at the time.