Chris Christie compares Trump to '72-year-old relative'

President Trump is a stubborn grandpa.

That's what former New Jersey Gov. Chris Christie said on Sunday during an interview with ABC's "This Week."

Christie, a former Trump advisor, likened the President to a "72-year-old relative" who refuses to change his or her ways.

“When people get older, they become more and more convinced of the fact that what they’re doing is the right thing and it becomes harder to convince them otherwise," Christie told ABC News.

Christie made the comments while discussing incoming White House chief of staff Mick Mulvaney and the challenges he faces working for Trump.

“I was encouraged by hearing him say he wasn’t going to try to manage the president," Christie told ABC News. "I think that one of the mistakes — I think a very well-intentioned mistake that Gen. Kelly made is that he tried to manage the president. I don’t think you can do that.”

Kelly is currently serving as Trump's chief of staff, but is leaving at the end of the year — along with Defense Secretary James Mattis.

"Manage the things you can manage," Christie told ABC News. "And if Mick does that, I think he'll be successful. If he doesn't, it'll be hard."