Vice President Kamala Harris has faced a barrage of racist attacks on her qualifications and background since President Joe Biden withdrew from the presidential campaign. On July 31, former President Donald Trump fanned those flames at the National Association of Black Journalists’ annual convention when he falsely claimed that Harris “happened to turn Black” only recently. The Trump campaign has doubled down on those accusations, too, repeating them several times over the past month.

If these attacks were meant to blunt Harris’s momentum, however, they haven’t worked. Trump has clearly lost ground in the polls since his NABJ appearance, and his rhetoric at the event was heavily criticized by the news media, Democrats and even some high-profile Republicans. It turns out, this was predictable. Survey data and political science research tells us there are three big reasons why Trump’s remarks will likely hurt his presidential campaign.

Trump is emphasizing one of his biggest liabilities

First, and perhaps most importantly, Trump’s attacks on Harris’s racial identity refocuses attention on arguably his weakest issue. I noted back in June 2020, for example, that Trump regularly received his lowest issue approval ratings for his handling of race relations. Trump’s net approval ratings (approval minus disapproval) on race were consistently around 30 percentage points underwater in 2019 surveys.

Those overwhelmingly negative assessments continued throughout his presidency. Voters gave Trump lower scores on race relations than on any other major issue in an October 2020 YouGov/Yahoo News poll. Biden led Trump by a whopping 22-point margin (53 percent to 31 percent) on the survey’s question about which candidate would do a better job of handling race relations as president — his biggest advantage over Trump across nine of the most salient issues in the 2020 campaign.

Voters, however, almost always rate ex-presidents’ performances more positively in retrospect, and Trump has experienced a similar “nostalgia bump” in retrospective approval of his handling of race and several other issues. His net approval rating for how he handled race relations during his presidency was only -11 points in an April 2024 New York Times/Siena College poll. Likewise, Biden’s advantage over Trump on the issue of race had dwindled to just 10 points in a June 2024 Suffolk University/USA Today survey.

Attacks on Harris’s biracial background by Trump and his allies, therefore, run the risk of reminding nostalgic voters of his presidency’s unpopular approach to race relations. They could pose an even bigger problem for Trump by making his poor performance on race a more prominent voting issue. Some political science research contends that the main goal of presidential campaigns is to emphasize advantageous issues so that they might factor more heavily into Americans’ votes.

Racist attacks against Harris, however, effectively do the exact opposite. Instead of emphasizing issues on which he has an advantage over the Democrats, such as immigration and inflation, Trump’s false attacks on Harris’s racial background refocus attention on one of his biggest political liabilities. In keeping with that contention, a clever experiment embedded in a new Fairleigh Dickinson University poll found that Harris’s lead against Trump grew significantly among voters who were primed to think about the candidates’ race and ethnicity ahead of time.

Rallying Black Americans to Harris

Harris was not particularly popular among Black voters when she jumped into the presidential race. As Samantha Canty and I wrote in July, Black people rated her significantly less favorably than they rated Biden throughout the first three years of their administration.

To be sure, Harris’s favorability rating among Black registered voters quickly surged from 71 to 82 percent in Civiqs’s daily tracking data soon after she became her party’s presumptive nominee. But a 538 analysis of polls conducted July 21-Aug. 17 still showed her trailing Biden’s 2020 vote margins among Black respondents. Black respondents also rated Harris 16 points less favorably than they rated former President Barack Obama in a YouGov/The Economist poll (69 and 85 percent, respectively) conducted just a few days before Trump’s NABJ appearance.

My research with Canty found that Harris underperforms Obama’s popularity by the widest margins among Black voters who score highest in measures of racial solidarity, such as rating Black people very favorably and saying race is very important to their identities. That’s bad news for Trump since these racially conscious Black voters are also the most likely to be countermobilized by racist attacks against Harris.

Political science research shows that voters who score highest in measures of racial solidarity are both the quickest to perceive discrimination against members of their group and to politically rally in defense of them. If anything, then, racist attacks on Harris should help solidify her support among the same racially conscious Black voters who had only felt lukewarmly toward her throughout most of her vice presidency.

Mobilizing racially sympathetic whites

Racist attacks against Harris could also backfire by countermobilizing white Americans who think anti-Black discrimination is a major problem in the U.S. After all, Obama offset race-based opposition in part by activating unprecedentedly strong support from such racially sympathetic white Americans.

Racial liberalism has become an even bigger political force in American politics since Obama’s presidency. The share of white Americans who viewed racial discrimination and systemic racism as major impediments to Black success increased dramatically during the Trump administration — especially among white Democrats.

But Democrats are far from the only ones who empathize with Black Americans who are treated unfairly. A new book on racial attitudes by Wellesley College political scientist Jennifer Chudy shows that most white people express either “a great deal” or “a lot” of sympathy with Black Americans who’ve experienced tangible instances of racial discrimination.

Overtly racist attacks against Harris should, therefore, only make her a more sympathetic figure among this large share of whites who empathize with Black people facing racial discrimination. Indeed, social science research has long suggested that explicitly racist campaign appeals are ineffective precisely because they violate most white Americans’ commitment to norms and principles of racial equality. And a recent book from Williams College political scientist Matthew Tokeshi shows that rebutting racist attacks against Black candidates tends to mobilize support from racially sympathetic whites.

* * *

There are other reasons why racist attacks against Harris might backfire as well. But regardless of the exact mechanism at play here, the data and research on issue advantages, Black voters and racially sympathetic white voters strongly suggest that there just isn’t an upside for Trump to employing racist appeals against Harris — especially when he had already maximized his vote share among racially prejudiced whites in the 2016 and 2020 elections.