“His numbers with Republicans are as solid as any recent Republican president—probably even more solid,” said Ryan Williams, a GOP strategist who worked for Mitt Romney’s presidential campaign in 2012. In poll after poll, an overwhelming majority of Republican voters—well over 80 percent—approve of Trump’s performance in office, even as nearly all Democrats and most independents give him a thumbs-down. “He’s unbeatable in a primary,” Williams told me…

Another advantage Trump has is that he already defeated an entire generation of Republican stars when he prevailed in a 2016 field that included Bush, then–Wisconsin Governor Scott Walker, and Senators Ted Cruz of Texas and Marco Rubio of Florida.

It also included Kasich, who has flirted with another try in 2020 and is planning a visit to New Hampshire next month. But the former Ohio governor said recently he’s in the camp of those who don’t think Trump can be beat in a primary. “When I run, I run to win,” Kasich said last week on CNN. “I don’t run to do damage. I’m not a stalking horse for anybody. So at this point, I don’t see a path. That doesn’t mean there isn’t a path in the future.”