President Trump’s incoming chief of staff, Mick Mulvaney, once publicly expressed great skepticism over Trump’s proposed border wall, calling it “absurd and almost childish,” CNN reported Friday.

The comments were made during a 2015 interview with Patti Mercer on WRHI radio in South Carolina, where Mulvaney doubted the necessity and effectiveness of a wall on the Mexican border, which then-candidate Trump repeatedly called for during his presidential campaign.

“Donald Trump says, ‘build a wall. Deport all illegal immigrants…’ What challenges does this plan pose?” Mercer asked Mulvaney.

“A bunch,” Mulvaney responded.

“The fence doesn’t solve the problem,” Mulvaney continued. “Is it necessary to have one? Sure. Would it help? Sure. But to just say build the darn fence and have that be the end of an immigration discussion is absurd and almost childish for someone running for President to take that simplistic of a view.”

A border wall between Mexico and the U.S. was a staple of Trump’s presidential campaign and is the center of a current partial government shutdown. The shutdown followed a standoff over funding $5 billion for the proposed wall.

Mulvaney went on to say in the interview that a wall will not stop anyone trying to get across the border. He said people trying to get across the wall can go under, around and through it. Mulvaney told Mercer that the best border protection strategy would be more manpower, enforcement and better technology.

“There are parts of our border that are secure and parts of our border that are not,” Mulvaney said. “A lot of that comes down to whether or not we are just willing to enforce the law as it exists. So it’s easy to tell people what they want to hear, ‘build the darn fence, vote for me.'”

Trump announced that Mulaney, who currently serves as the director of the Office of Management and Budget, would be his next chief of staff on Dec. 14, after John Kelly handed in his resignation. Mulvaney then tweeted that it was a “tremendous honor.”

“I look forward to working with the President and the entire team. It’s going to be a great 2019,” he said.

https://twitter.com/MickMulvaneyOMB/status/1073709695809056768

Get our Politics Newsletter. The headlines out of Washington never seem to slow. Subscribe to The D.C. Brief to make sense of what matters most. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Gina Martinez at gina.martinez@time.com.