There is evidence, it appears, that the party of George W. Bush, John McCain and Mitt Romney was not merely the party of Trump in waiting. “Trump support,” say the authors, “is uniquely dependent upon out-group hatred.” This is not a normal sort of partisanship. It is partisanship supercharged by prejudice and contempt. This fits the experience of elected Republicans I have interviewed, many of whom no longer recognize the political party they rose within. The players and attitudes in many states and districts have shifted. Something different and disturbing is taking place.

Trump did not create this out-group animosity; he exploited it, organized it and sent it into political battle. “Even in the 2016 Republican presidential primary,” the authors note, “out-group hatred predicted support for Trump, but not for [Ted] Cruz, [Marco] Rubio or [John] Kasich.” They go on: “We tend to think of partisans as being generally intolerant of outsiders, but our findings suggest that Trump supporters are unique in terms of their out-group hatred.”

This offers the comfort of knowing that the whole GOP is not united and defined by contempt for outsiders. But the indictment of the Republican non-haters is still quite damning. In every way that matters politically, they have accepted the leadership of a president and a movement that cultivate hatred as a strategy.