For years, prospective Democratic nominees came to Iowa to talk ethanol and pork subsidies and saved any rhetoric about the injustice of racial profiling for crowds in South Carolina and Nevada — the only early voting states where black and Latino voters made up a significant portion of the Democratic electorate.

But in the era of Mr. Trump, and after social movements such as Black Lives Matter pushed racial inequality to the forefront of national politics, it’s white Democrats in Iowa and New Hampshire — not black ones in South Carolina — who, to this point, are embracing the candidates who promise to upend society in the name of racial equity…

“My daughter is marrying an Asian man and diversity has become very important to me,” said Julie Neff, a 57-year-old Iowa Democrat who attended the Harris rally. Ms. Neff, who is white, said she was embarrassed that she started thinking about race and discrimination only later in life.

“I should’ve been paying attention to this stuff sooner. But when Trump is making these decisions, I just realized it would be bad for my son-in-law and my grandchildren,” she said.