Democratic presidential candidate, former Vice President Joe Biden speaks during a campaign rally at Eakins Oval in Philadelphia, Saturday, May 18, 2019. (Matt Rourke)

For Democrats, it is unquestionably the case that having a white man on the ballot next November will spur turnout and energy among even infrequent voters. That white man is President Trump, whose unpopularity with members of the opposing party led to midterm turnout that we hadn’t seen in a century.

It’s an open question, though, how having a white man representing their own party might boost or dampen Democratic enthusiasm. New data from Pew Research Center, though, suggest that nominating another white man might be problematic for the party.

Most Democrats are white, but far more of the party is nonwhite than is the case with Republicans. About a fifth of Democrats are either black or Hispanic, compared to 8 percent of the GOP according to Pew data released last year.

(Philip Bump/The Washington Post)

Black and Hispanic Democrats told Pew this month that, overall, having a white Democratic nominee wouldn’t really affect their enthusiasm. Among those who did say that a white nominee would affect their enthusiasm, respondents were more than twice as likely to say that their enthusiasm for a white candidate would be lower than higher. (Among white Democrats, it was basically a wash.)

(Philip Bump/The Washington Post)

The same wasn’t true of a hypothetical black nominee. Among black Democrats in particular, respondents indicated much more enthusiasm. White Democrats were five times as likely to say they’d be more enthusiastic than less enthusiastic.

(Philip Bump/The Washington Post)

The same held true for a hypothetical Hispanic nominee. Hispanic Democrats expressed far more enthusiasm about the prospect, but white and black Democrats did, too.

(Philip Bump/The Washington Post)

The difference between the apathetic response to another white nominee and a potential nominee of color was stark. But not as stark as the other option that Pew presented: What if the nominee were a white man?

Most respondents still said that such a candidate wouldn’t affect their enthusiasm. But among those who did think it would affect their enthusiasm? They were far more likely to say that their enthusiasm for such a candidate would wane.

(Philip Bump/The Washington Post)

Why does this matter? In part because of an under-recognized trend in the 2016 election.

That year, an estimated 4.4 million voters who’d supported Barack Obama in 2012 didn’t cast a ballot. More than half of those Obama voters who didn’t vote in 2016 -- the top bar on the graph below -- were nonwhite.

(Philip Bump/The Washington Post)

That’s the concern for Democrats: That an election in which Trump’s base is motivated to send Trump back to the White House will be met with a Democratic base that isn’t similarly motivated. Trump already has an advantage in that Republicans vote more consistently than do Democrats. Any decline in enthusiasm among Democrats could mean the sort of skin-of-his-teeth victory that Trump enjoyed three years ago.

Again, it might not matter. Trump’s going to mobilize Republicans, but we can’t underestimate how significant a motivation he is for Democrats, too. It may end up being the case that any Democrat would fare as well as any other against Trump when it comes down to turnout simply because Trump is so energizing for the left.

But in an election where Democrats don’t want to leave anything to chance, more than 15 percent of Democrats saying that a white male nominee will dampen their enthusiasm to vote is something to which the party might want to pay attention.