Republican pollster Frank Luntz said early Friday that if he was to give advice to former President Trump, he would tell him “to stop behaving like a petulant child.” “If I were advising him, which I am not, I would look him straight in the eye and say, ‘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 said on “CNN This Morning” with anchor Kasie Hunt. Republicans have pushed Trump to focus on policy differences...