Have you EVER heard Trump say 'I was wrong', or 'I made a mistake'? He lost a billion dollars in the casino industry (though his own bad decisions and mismanagement), and later, when asked about it he said 'It was a tough business but I did okay!'
He's unable to admit that his party's own polls show hm less popular than Elizabeth Warren in TEXAS. In his mind, to acknowledge that would be an admission of failure. So he doesn't.
During all of Trump's business career nobody ever challenged him. "Whaddya mean you DID OKAY in the casino business? You lost a billion dollars!" Reporters don't do that with a businessman because it doesn't really matter. But he doesn't understand why people do that now that he's president. "Whaddya mean you're leading in all the polls? They're you're own party's polls!" He sees that as an insult, a deliberate contradiction of something he said. It's not the truth of the matter that's important, it's the attack on his image. Nobody did that to him before, and he doesn't know how to handle it!