One explanation for Republican Roy Moore’s staying power against Democrat Doug Jones in the Alabama U.S. Senate race might center on policy preferences. Moore’s closing pitch seems all about abortion, with a caboose of other Christian-conservative policies. Alabama voters are especially conservative, so this might seem logical.

And in many ways it echoes the 2016 presidential contest, where voters in a few swing states seemed willing to put aside Donald Trump’s transgressions in the hope that his policies would make America great again. Much commentary since the election has indeed focused on how Hillary Clinton and the liberals overlooked the plight of white, working-class Americans, for instance, and all good progressives now have J.D. Vance’s memoir “Hillbilly Elegy” on their nightstand.

The problem is that, in both cases, a policy-centered explanation is wrong.

Beginning about a decade ago, our politics took a radical turn. Elections became exceedingly partisan. Straight-ticket voting, for example, has reached unprecedented levels.

More importantly, the very meaning of “party identification” has changed. Whereas in the past, our attachment to a political party centered on policy disputes or cues from family and associations, today’s version is grounded in fear and loathing of the other side. We believe that members of the “other” party are crazy, dangerous, a true threat to the nation.

Pew Research Center data tell the story: Politics was rather heated in 1994, as you may recall, but that year only about 21 percent of Americans had a “very unfavorable” view of those in the other party. Today, that figure stands at 58 percent. Many other studies point to increasingly hostile attitudes toward members of the other party. We don’t trust them and are less likely to socialize with them or to hire them. About a third of Americans say they would be upset if a member of their family married one of “them.” Playdates with conservative/liberal kids? I don’t think so!

At the end of the Obama administration, the Pew Center reported, 59 percent of Republicans said they felt “very coldly” toward Michelle Obama, and 40 percent of Republicans gave her a zero on a scale of 1 to 100. Michelle Obama gets a zero?

As noted by Emory University scholars Alan Abramowitz and Steven Webster, “Over the past few decades, American politics has become like a bitter sports rivalry, in which the parties hang together mainly out of sheer hatred of the other team, rather than a shared sense of purpose.”

We choose to live in ideologically homogenous communities, and the promise of the internet to broaden perspectives and associations has morphed into blinders and the purifying of sources, arguments and facts. Voters no longer explore new ideas and perspectives, but share, like and retweet concordant ones. Adding fuel to the fire, a new book by scholars Chris Achen and Larry Bartels has shaken our understanding of voter rationality.

“Issue congruence (between voters and parties), in so far as it exists, is mostly a byproduct of other connections, most of them lacking policy content,” they write. Voters align themselves with racial, ethnic, occupational, religious, recreational and other groups.

Group identity determines vote choice, not policy preferences. People do not seem to understand or even like the policy choices they make.

So when Donald Trump tells votes in Alabama that Doug Jones is a liberal, and when Steve Bannon says that Roy Moore is “righteous,” they’re ringing the tribal alarm. Sure, Moore might have done those things to teenage girls, but at least he’s one of us.

And as to the economic interpretation of Trump’s win, a growing pool of studies suggests attitudes toward immigration, blacks and social welfare were much more important than were perceptions of personal finances or the state of economy.

It’s hard to label Donald Trump strategic these days, but he seems to know what he’s doing when he tweets “We need (Moore’s) vote on stopping crime, illegal immigration, Border Wall, Military, Pro Life, V.A., Judges 2nd Amendment.”

Ring that tribal bell, Mr. President. Ring that bell.