So Frank was wrong … or maybe he was prescient. Because he was writing just before Bush won re-election to a second term without a clear middle-class agenda, which led to the unpopular pushes for Social Security reform and an immigration amnesty and to the collapse of Bush’s political position. Then after Obama’s election the G.O.P. lurched away from the middle class in a more stark way than it ever did under Reagan or Bush or the Newt Gingrich speakership, embracing theories about how the working class was actually undertaxed, rallying around tax plans that seemed to threaten middle-class tax increases and promoting an Ayn Randian vision in which heroic entrepreneurs were the only economic actor worth defending.

The success of Donald Trump’s populist candidacy seemed like a partial repudiation of this Randian turn, and a possible return to the middle-class-focused politics that had made Reagan and Bush successful — albeit in a more aggressively nationalist and mercantilist form. But as president, Trump has essentially become the Frankian caricature in full, draping the rhetoric of populism over an agenda that so far offers little or nothing to the middle class, making appeals to the religious right that are notable in their cynicism, and rallying his base through culture-war controversies distinguished mostly by their ginned-up phoniness.

So “What’s the Matter With Kansas?” was a poor guide to the party of Reagan and George W. Bush, but thus far it is a very useful guide to the Trump administration. And two possible takeaways from this shift seem worth considering.

The first is that, for all its failures, not everything about the Bush era was disastrous, and there were ways in which the Bush White House had a clearer sense of what conservatism should offer to the common man than any its would-be successors have come up with since.

This doesn’t excuse the disaster of Iraq or the various problems with Bush’s domestic agenda, including the way that one of his middle-class-friendly policies, the push for homeownership, contributed to the housing bubble and the crash. But it is still a mistake for the right to dismiss the Bush agenda as merely “a failure and a fraud,” as my friend Peter Suderman did recently in these pages, and also a mistake for liberals to suggest that Trump is just returning to the Bush playbook, as New York’s Jonathan Chait did in a recent piece.