“At that point, what you’re looking at is this sense of powerlessness all around about the ability of any institution to mediate not just a political conflict, but a conflict of fundamental values,” she said. “That’s maybe something like what we’re dealing with right now.”

The Senate’s rancorous fight over Judge Brett Kavanaugh’s confirmation, she added, has similarly added to pessimism about resolving these conflicts.

In the two years since Mr. Trump’s election, protesters and politicians on the left have lamented the erosion of values around tolerance and diversity. On the right, they have continued to mourn the loss of religious and traditional family values at the center of American life.

Ms. Hochschild identifies as a liberal herself, and after Mr. Trump’s election, she said one of the conservative voters she described in her book sent her an email.

“She said, ‘Well, I guess it’s now your time to feel like a stranger in your own land,’ ” Ms. Hochschild said. She acknowledges that she has felt this way of late, as she has watched President Trump declare the free press the enemy of the people and question the independence of the judiciary. “I had no idea we could come this far this fast and challenge things I thought were basic,” she said. “It feels like some pillars of our culture are being shaken, stress-tested.”

That is precisely the feeling she had described in Louisiana.

On other survey questions, Democrats and Republicans sometimes swap views depending on which party is in power. Republicans, for example, have become much more upbeat about the economy and their own finances, and Democrats less so, since Mr. Trump took office.

But it does not seem, with Mr. Trump in power, that partisans have simply traded views on who feels estranged. And that is part of what makes this moment unusual. Even as the Trump presidency has troubled Americans who didn’t vote for him, the president has continued to repeat the messages that helped him appeal to disaffected voters in the first place. And he has told his voters that he and they have not been accepted by institutions like the news media, the entertainment industry, academia and even some of corporate America.