But this is not a strategy without risk, Mr. Goldberg noted. Voters in a general election, including Republicans and independents, do not share the liberal views about race that white Democrats do. Positions that some leading Democrats have embraced, including reparations for black Americans, could become liabilities.
“When you think about it, this is why blacks may be supporting Biden the way they do,” Mr. Goldberg said. “They know this may not sell to the rest of white America come general election time.”
In the early days of Ms. Warren’s candidacy, the differences among Democratic primary voters were most clear when she discussed low black homeownership rates — a standard portion of her policy-heavy stump speech. Black audiences in Mississippi and Alabama often seemed unmoved, already well aware of the problem Ms. Warren outlined. In Iowa, predominantly white groups reacted dramatically — often with oohs and ahhs and the occasional applause.
At events for Ms. Harris last week, several white voters said that the president’s reliance on white identity politics to motivate his conservative base had forced them to reorganize their own voting priorities.
Ms. Neff’s husband, Bill, wore a Black Lives Matter T-shirt to the evening rally.
“We had Obama and we thought this racial stuff was over — and then we went backward,” he said. “We’ve seen so many old white guys who are O.K. with the status quo, and that’s not O.K. anymore.”
People like the Neffs and Mr. Olsen could have an outsize effect on the 2020 primary, and the Democratic Party going forward. The largely white voters in the earliest nominating contests in Iowa and New Hampshire determine which candidates appear viable by the time people in more diverse states head to the voting booth.
Barack Obama famously exploited this playbook in 2008, winning white liberals in Iowa before unlocking his support among black voters. This year’s most prominent black candidates — Mr. Booker and Ms. Harris — are both seeking to repeat that strategy, and have staked their candidacies on a good showing with those same white liberals in the first-in-the-nation caucus.