The issue of police violence entered the 2020 campaign with the death of George Floyd

Video footage from Monday shows George Floyd saying “I can’t breathe” as an officer pinned him to the ground. That footage went viral within hours. The four officers at the scene of the arrest were fired Tuesday, and protesters have taken to Minneapolis streets in the nights since.

The incident, and President Trump’s and presumptive Democratic nominee Joe Biden’s responses to it thus far, are giving us a lens through which to view their political calculations regarding the challenges of appealing to diverse voting blocs: black Americans deeply angered by police violence, suburban voters uncomfortable with the country’s racism, and Americans who are sympathetic to police and want a leader who will be tough on crime.

The story had been grabbing headlines for a day and a half before Trump’s first public comments on it Wednesday in a pair of tweets. White House press secretary Kayleigh McEnany said Thursday that Trump was being briefed on Floyd’s death by Attorney General William P. Barr.

Former vice president Biden tweeted about Floyd’s death on Tuesday, and on Wednesday he called for a civil rights investigation.

“Watching his life be taken in the same manner and echoing nearly the same words of Eric Garner more than five years ago — ‘I can’t breathe’ — is a tragic reminder that this was not an isolated incident but a part of an ingrained systemic cycle of injustice that still exists in this country,” Biden said Wednesday in a virtual event. “It cuts at the very heart of our sacred belief that all Americans are equal in rights and in dignity. And it sends a very clear message to the black community and black lives that are under threat every single day.”

The Black Lives Matter movement became a major campaign focus during the 2016 presidential election. Trump’s reaction to deaths and to protesters then was twofold: He expressed concern for black Americans killed by law enforcement. But he also embraced the strongman persona that made him popular with his largely white, working-class and male base, by saying at one point that he’d “do the fighting myself” rather than tolerate activists interrupting his rallies.

Trump maintained this approach early in his presidency. In 2017, he encouraged police to be forceful with suspects and later that year called for the firing of NFL players protesting racial injustice. That has certainly played a part in keeping his approval rating with black Americans low. Those ratings haven’t kept his campaign from launching outreach efforts to black voters with the hope of putting a dent in Biden’s lead with the demographic and perhaps as importantly, assuaging the concerns of white voters who are uncomfortable with Trump’s sometimes blatantly racist language.

Biden is leading significantly with black voters — 81 percent support him, according to the most recent Quinnipiac University poll, and he is expected to win the demographic in November. But gaffes on racial matters, including a big stumble last week in an interview on “The Breakfast Club,” and lingering questions about his past policies, have left him in the hot seat with some black voters, particularly those under 40, even after he has all but officially sewn up the Democratic nomination. In a race where the margins matter, showing deep concern about violence against black men could be key to helping black men turn out for Biden, a former lawmaker who supported tough crime laws in the 1980 and 1990s that led to an increase in the number of black men who were incarcerated.

Both candidates have called for justice for Floyd’s family — something that probably appeals to a broad swath of Americans. But both have also praised Minneapolis officials for their response to the officers involved in Floyd’s death.

How the candidates continue to respond to this incident could be a factor in the campaign for its duration. What will be worth paying attention to isn’t just how they each respond to the incidents and the law enforcement officers, but also to activists and the voters who are sympathetic to their plight.

Biden’s success has been largely due to the loyalty of black voters, but also to eating away Trump’s support with suburban voters and white working-class voters. Trump in 2016 narrowly won, and in doing so he performed better with black men and some white Christians than did previous Republican candidates. Victory in November could not only come by mobilizing the bases but by also eating away at voters who have historically backed the opposing candidates’ party. The candidates will have to figure out a way to do this without losing the support of the voters who have backed them most.