Incoming White House acting chief of staff Mick Mulvaney once derided President Trump’s proposed border wall as “simplistic” and “absurd and almost childish,” it was reported Friday.

Mulvaney trashed Trump’s border wall during a 2015 interview uncovered by CNN.

“Donald Trump says, build a wall. Deport all illegal immigrants. Rules are rules. You either play and stay or you cheat and you get deported. What challenges does this plan pose?” then-Rep. Mulvaeny was asked in the August 25, 2015, interview on WRHI radio in South Carolina.

“A bunch,” Mulvaney responded.

“The fence doesn’t solve the problem. 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,” Mulvaney added, without making a distinction between a fence or wall.

Mulvaney was White House budget director before Trump tapped him to become acting chief of staff, a position in which he would be assigned to lead the president’s charge to build a wall along the U.S.-Mexico border.

Mulvaney in 2015 claimed a barrier would not stop illegal immigrants from crossing the border and ranchers told him they don’t need a fence.

Mulvaney said enforcing the current law with more manpower and better technology would bolster border patrol — something Trump is promoting.

“And by the way, the bottom line is the fence doesn’t stop anybody who really wants to get across,” Mulvaney said in the interview.

“You go under, you go around, you go through it. And that’s what the ranchers tell us, is that they don’t need a fence. What they need is more manpower, and more technology, and more willingness to enforce the law as it exists today. There are parts of our border that are secure and parts of our border that are not. 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.’”

He said Trump was appealing to people’s anger during the campaign, but that doesn’t solve the problem.

“And I get it because I’m as angry as they are, but just to appeal to somebody’s emotion and say, vote for me because I’m as angry as you are, doesn’t really solve the problem. It might make you feel better in terms of having voting with somebody who sympathizes with you, but it doesn’t really solve the problem and that’s what I’m interested in trying to do is, how do you solve the problems and winning elections is part of solving the problems,” Mulvaney said.

The Daily Beast last week reported that Mulvaney called Trump “a terrible human being” during a November 2016 congressional debate.

CNN reported on Monday that Mulvaney also said in October 2016 Trump would be disqualified from office in an “ordinary universe.”

Mulvaney will replace John Kelly as chief of staff.