In a March 2019 study, “White People’s Racial Attitudes Are Changing to Match Partisanship,” Andrew Engelhardt, a political scientist at Brown, explored changing views among whites from 2016 to 2018, based on surveys conducted by American National Election Studies. Tracking a measure of white views of black Americans, he found that there has been:

A profound shift in whites’ evaluations of black Americans in just a two-year period. The modal white Democrat moves from placing at the scale’s midpoint in 2016 to locating at the scale’s minimum (least racially resentful) in 2018. For Republicans, the modal respondent still places at the scale’s maximum (most resentful), but the percentage of white Republicans here increases from 14 percent to 21 percent. While these shifts may seem small given the scale, I show below they represent a rather substantial change on a measure that has otherwise evolved quite slowly since the 1980s.

On a separate American National Election Studies thermometer measure of group favorability, where 0 is very unfavorable and 100 is very favorable, Engelhardt reported that:

In 2018 Democrats rated black people at a 77, up 7 points from 2016. But they rated whites at a 70, a 2 point decrease. Republicans’ feelings about black people improved slightly (64 vs. 69) in these two years but this was far outpaced by increased warmth toward white people (74 vs. 81). While Republicans consistently feel more positively about white people than black people, white Democrats’ attitudes look quite different. White Democrats now feel more warmly toward black people than white people.

Engelhardt’s findings lend support to the views of Alexander Theodoridis, a political scientist at the University of California-Merced, who contended in an email that

For most people, party identity appears to be far more central and salient than particular issue positions. We see increasing evidence of people adjusting their issue positions or priorities to fit their party allegiance, more than the reverse. We are very good at rationalizing away cognitive dissonance. More important than this chicken-or-egg question is the reality that ideology and party have become very highly sorted today. Liberal and Conservative are now tantamount to Democrat and Republican, respectively. That was not always the case. Furthermore, all sorts of descriptive and dispositional features (ranging from religion and race to personality type and worldview) are also more correlated with political party than they were in the past. All this heightens the us-versus-them nature of modern hyperpolarization.

This debate is sometimes framed in either-or terms, but the argument is less a matter of direct conflict and more a matter of emphasis and nuance.

Yphtach Lelkes, a professor of political communication at the University of Pennsylvania, wrote me that “ideology and partisanship are very hard, and likely impossible, to disentangle,” but, he argued, the larger pattern appears to be that

while both seem to be occurring, ideology driving partisanship only seems to be occurring among those that are most aware of politics, while partisanship driving ideology seems to be happening among everyone.

Similarly, Leonie Huddy, a political scientist at SUNY-Stony Brook, wrote me that the debate “is more complicated than simple tribalism versus consistent ideology.”

There is “clear evidence of partisan tribalism,” Huddy observed, “especially when it comes to a potential win or loss on matters such as impeachment, presidential elections, and policy issues central to electoral victory or defeat,” but at the same time