Former New Jersey Gov. Chris Christie (R) on Sunday compared President TrumpDonald John TrumpWarren: 'White supremacists pose a threat to the United States like any other terrorist group' National Enquirer paid 0,000 for Bezos texts: report Santorum: Trump should 'send emails to a therapist' instead of tweeting MORE to a “72-year-old relative,” saying that it’s hard to convince them they’re not doing the right thing.

Appearing on a panel Sunday on ABC's "This Week," Christie said that it would be a challenge for Trump’s aides to get him to change his behavior.

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“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."

He made the comment while discussing Trump’s appointment of White House budget director Mick Mulvaney as his acting chief of staff, saying that Mulvaney will be successful if he doesn’t “try to manage the president.”

Christie’s comments were met with laughs and head shakes from fellow panelists, including former interim Democratic National Committee Chairwoman Donna Brazile.

“It’s happening to me now,” Christie joked.

Christie, a former Trump campaign and transition adviser, last week said he turned down the offer to replace John KellyJohn Francis KellyMORE as Trump’s new chief of staff.