Why did Trump win? For two reasons. First, the voters in these contests are the party’s activist base, and Trump fundamentally reshaped that base during his first run for president and his White House years. He moved the party sharply away from its center-right traditions toward populism, away from free trade and international alliances toward nationalism. His slogan, “America First,” encapsulates those changes. So do his strenuous efforts to limit illegal immigration and roll back the Administrative State.

Second, the former president remained atop the party because his campaign appearances reassured the base that he is the same energetic, entertaining, anti-Establishment candidate they have supported ever since he rode down the Trump Tower escalator in 2015. They like his policies; they love his attacks on entrenched elites; they think the legal cases against him are unfair, political prosecutions; and they firmly believe he can defeat a weak President Biden. They see no compelling reason to switch their allegiance to another Republican.

The depth and durability of this bond between Trump and his supporters is obvious now, but it wasn’t when the primary season began.