Republican pollster Frank Luntz delivered a blunt message to former President Trump on Friday, urging him to “stop behaving like a petulant child” and to make a significant change in his approach.

Speaking on “CNN This Morning,” Luntz told anchor Kasie Hunt that if he were advising Trump, he would firmly tell him, “Sir, you need to shut up. You need to stop behaving like a petulant child, and start focusing on what the American people want, in a way that they want to hear it.”

Luntz’s critique comes amid mounting pressure on Trump from Republicans to shift his focus from personal attacks against Vice President Kamala Harris to substantive policy discussions. Harris has gained momentum within the Democratic Party, spurred by recent uncertainties about President Biden’s 2024 candidacy.

Luntz warned that Trump’s current approach could have serious repercussions.

“Look, if I yell at you every time you have me on, you’ll stop having me on and you’ll stop listening,” he said, emphasizing the need for Trump to heed honest feedback. He cautioned that if Trump continues his current behavior, Harris might secure a significant lead following her convention, suggesting she could hold a 5- or 6-point advantage over Trump.

“Trump doesn’t understand that. People have to tell him the truth, because at this point she’s got her convention bounce before the convention, and I think Harris could have a 5- or 6-point lead coming out of that convention if Donald Trump continues to behave the way that he has,” he concluded.

Recent polls reflect Harris’s rising position, with an average national lead of 2 points over Trump. Polling from The New York Times/Siena College also shows Harris ahead by 4 points in key battleground states like Michigan, Wisconsin, and Pennsylvania.