Research is beginning to suggest that white voters who have long been politically motivated by their views of other groups may be starting to think of their own group as an explicit identity. In that sense, they appear for the first time in the Trump era to be thinking about themselves in ways that mirror how minorities have long thought about group identity.

It wasn’t a foregone conclusion that American politics would end up here in 2019, with voters chanting to send a foreign-born American congresswoman back to Africa. A different politician at the top of the Republican Party — one focused, say, on tax cuts rather than immigrants — might have left these white racial anxieties more dormant, or less clearly linked with partisanship.

That means this moment shouldn’t simply be understood as a backlash against the country’s first black president, political scientists say. It is also a response to the first president in the modern era to make explicit appeals to white racial anxieties the central focus of his campaigns.

“All of a sudden, these people who had no vehicle to express these attitudes are now being invited to express them,” said Lynn Vavreck, a political scientist at U.C.L.A. and occasional Upshot contributor, and a co-author of a book with Mr. Tesler and John Sides on the role of racial identity in the 2016 election.