Mr. Trump has a talent for the populist art of reflecting supporters’ instincts, feeding off them and intensifying them. Mr. DeSantis, instead of intuiting this potential, merely mirrored a position to an audience already primed to accept it. Mr. Trump, with his bloodhound’s nose for potential weakness in his competition, dismissed Mr. DeSantis as a copycat who is merely “following” him. “Whatever I want, he wants,” Mr. Trump said in March after Mr. DeSantis’s initial statement on Ukraine. Ms. Haley, Mr. Trump’s former ambassador to the U.N., who is herself running for president this cycle, also accused Mr. DeSantis of “copying” Mr. Trump.

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