Eric Thayer / Reuters

Donald Trump today just solved Hillary Clinton’s biggest strategic problem: how to ensure that minority voters show up for her in 2016 as they showed up for Barack Obama in 2012.

Post-Obama Democrats face a quandary: Their coalition is bigger than the Republican coalition, but also less committed to political participation. When voter turnout drops, as it does in off-year elections like 2010 and 2014, Democrats lose.

In 2012, Democrats mobilized a truly heroic turnout effort to re-elect President Obama. Black voter turnout in particular excelled: For the first time in American history, it surpassed white turnout. The extraordinary organizing effort of the Obama re-election team certainly deserves much of the credit. But organization can only ever do so much. Black voters turned out in huge numbers, exceeding even 2008 turnout, because they believed they had an important personal stake in the vote.

Earlier in the cycle, many wondered whether Hillary Clinton could generate anything like that kind of response from the Democratic base. “Will Black Folks Deliver for Hillary Clinton?” asked The Root in the spring of 2015. Charles D. Ellison, a keen student of African American voting, deployed an impressive mass of statistics and history to answer, in effect: “We’ll see.”

But here’s one observation of Ellison’s that the unexpected events of 2016 has already disproven.

"Ultimately, how strong or how soft the black vote will be is up to Hillary Clinton as both person and candidate.”

Instead—as with so much else this cycle—the black vote, like the women’s vote, like the Latino vote, like the divisions in the Republican Party, is being decided by Donald Trump.

Reportedly frustrated by Paul Manafort’s attempts to impose message discipline upon him—apparently determined to win or lose speaking his own thoughts in his own words—Donald Trump has done two astonishing things in the past 24 hours. The first was to replace his former campaign CEO with the head of the provocative Breitbart website, Steve Bannon. The second was to travel to West Bend, Wisconsin, a city almost 95 percent white and 40 miles from Milwaukee, to “reach out” to black America by defending the police of Milwaukee against their critics.

On Saturday, a Milwaukee officer shot a suspect dead. The shooting was followed by riots. Trump denounced the riots, as he should. But he had not a word of comfort or consolation or even human fellow-feeling to say to the black Americans—and other Americans who feel targeted and victimized—and he did not even have the nerve to speak his “the cops are right” message to the faces of those who might think differently. Let Trump be Trump!

Trump is surrounded by people who think it’s 1968 all over again, with white Americans ready to respond to a message of firm suppression of nonwhite disorder. But even after the crime uptick since 2014, the United States remains a very safe society—with crime a distant worry for the voters a normal Republican presidential candidate should now be seeking. The police-violence issue, however, does matter overwhelmingly to the black Americans whose turnout Hillary Clinton so desperately needs. Trump just cranked up the volume of the issue that helps her most—and his new team is made up of people likelier to crank it up louder still.

The defense of violent police force within and against troubled black communities looks likely to be elevated by the Breitbartized Trump campaign to the top of its agenda. Hillary Clinton could not wish for more. Down ballot Republicans could not fear worse.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.