From the start, Joe Biden has framed his candidacy around the concept of unity. In his campaign kickoff speech last year, he accused President Donald Trump of fanning, rather than working to bridge, partisan and racial divides – evoking a nation that, in his view, was yearning to come together.

“The country is sick of the division. They’re sick of the fighting,” the former vice president said in Philadelphia.

“Our Constitution doesn’t begin with the phrase ‘We the Democrats,’ ‘We the Republicans,’” he said. “We are all in this together. We need to remember that today, I think more than any time in my career.” 

Mr. Biden’s decisive primary victories earlier this spring seemed to affirm that view. But as the campaign now moves into the general election phase – after a stretch of tumultuous events nearly unprecedented in modern U.S. history – the task of unifying the nation has never seemed more daunting.

The past three months have upended politics as usual, with the pandemic taking more than 100,000 American lives and sending the economy into a tailspin that has left millions unemployed. Over the past two weeks, the death of George Floyd at the hands of Minneapolis police has sparked massive protests for racial justice across the country.

For Mr. Biden, the volatile landscape is presenting an increasingly challenging balancing act. He is under renewed pressure to shore up support among progressives who have been less enthusiastic about his candidacy, without alienating the swing voters who had been moving in his direction. Above all, he must somehow convince a fractured and exhausted nation that the problems it faces are fixable – and that finding consensus on those challenges is both possible and desirable.

“He’s being challenged to balance all these things, because Trump has so utterly failed to balance them,” says Democratic Sen. Chris Coons of Delaware. “This is a moment that demands leadership from someone who understands how to respond to a pandemic and bring us together. ... I think [Mr. Biden] is exactly the right man for the moment.” 

A healer in chief?

Mr. Biden has seized multiple opportunities in recent weeks to try to cast himself as a healer in chief.

On the same day U.S. Park Police in Washington cleared a group of peaceful protesters from Lafayette Square with tear gas and rubber bullets so that Mr. Trump could pose for a photograph outside historic St. John’s Church, Mr. Biden was sitting in a black church in Wilmington, Delaware, listening to community leaders from 6 feet away. 

Less than 24 hours later, Mr. Biden gave a speech in Philadelphia to a country he described as “crying out for leadership.” He called on Congress to enact a law banning police chokeholds and to create “a model use-of-force standard.” He also promised to create a national police oversight commission. 

On Monday, Mr. Biden was scheduled to meet privately with the Floyd family, and he is expected to attend Mr. Floyd’s funeral in Houston on Tuesday.  

“Biden is calming at a time when people are hearing nothing but nasty noise, and that juxtaposition is to his advantage,” says Jeff Link, an Iowa-based political consultant who has advised several Democratic presidential candidates. “Biden doesn’t have to outshout Trump, but he has to show how he’s different.”

Mr. Biden has deep reservoirs of affection in the African American community, among whom he built enduring relationships during the Obama years. It was black voters who carried him to a resounding win in South Carolina, reviving a candidacy that had appeared to be on its last legs, and ultimately helping make him the Democratic nominee. He officially secured the 1,991 delegates needed to claim the nomination this weekend.

But he is viewed less favorably by a younger, more left-wing generation, which sees him as too moderate to bring about needed change. Mr. Biden does not support calls to “defund the police,” which has become a rallying cry on the left in recent days. While he favors increased spending on other social programs, his campaign said Monday, he wants to increase, not decrease, police budgets for things like body cameras and training. 

Mr. Biden has long-standing ties to union groups, including cops and firefighters, some of which have been trending more conservative in recent election cycles, and which Democrats were hoping to win back this year. In recent days, some law enforcement groups have expressed unhappiness with what they see as Mr. Biden’s failure to demonstrate sufficient support for their side, showing just how difficult it may be for him – or anyone – to bridge those divides.

In a poll released last week by Monmouth University, 89% of Democrats said they had “no confidence at all” in Mr. Trump’s ability to handle race relations. But only 32% of Democrats had a “great deal” of confidence in Mr. Biden on the matter. Among Republicans, 58% had a great deal of confidence in Mr. Trump, while 58% had no confidence at all in Mr. Biden.

Protesters gathering around a graffitied Robert E. Lee statue in Richmond, Virginia, last week said recent events had heightened their expectations of Mr. Biden from just two weeks ago. 

“He thinks he’s automatically got the black vote because he was the right-hand man to a black president,” says Chenae Kirkland. “But he’s got to have a hand in these police departments, show us what he’d do,” adds her friend Leshayne Vialet, both bank employees.

Making promises is better than a photo op, they say – but it’s not enough. 

Some express concerns about Mr. Biden’s own track record during his 36-year career in the Senate. In the 1970s, he was a vocal opponent of school busing, and he helped write the 1994 crime bill, which many believe was a key contributor to mass incarceration that has disproportionately affected black men. 

“I felt like he was involved with all the stuff that’s led to where we are now,” says Andre Lynch, an Uber driver, gesturing to the dozens of activists climbing up the Lee statue. He adds, “When he ends up running this country, he’ll have a chance to redeem himself, especially after watching all of this unfold.” 

“It’s not about him”

Of course, to have that opportunity, Mr. Biden needs to win the election. Recent polls have shown him gaining ground against the president. According to a Fox News survey, Mr. Biden is now ahead in Wisconsin, Ohio, and Arizona – all battleground states the president won in 2016, while the Monmouth poll has Mr. Biden with an 11-point lead over Mr. Trump overall. But these polls are mostly about Mr. Trump, says Patrick Murray, director of the Monmouth University Polling Institute. 

“More so than any prior incumbent election, this is a referendum,” Mr. Murray says. But Mr. Biden still has to “get out there” and prove himself to Democratic voters.

And Mr. Biden faces unique challenges when it comes to unifying his party, not least because of COVID-19, says Robert Shrum, a longtime Democratic strategist and director of the University of Southern California’s Center for the Political Future. For three months, all campaign rallies have been canceled or turned into awkward “virtual” events, making it difficult for a candidate who thrives on rope lines and personal connections to reach voters.

The nominee’s acceptance speech at the party convention is typically an important moment, notes Mr. Shrum. “Just look at Al Gore in 2000,” he says. “He gained 15 to 18 points in 47 minutes.” But this year’s Democratic convention is increasingly looking like it will be held online, diminishing Mr. Biden’s ability to generate a big bounce. 

It’s also unclear if televised debates between the candidates will happen. In a debate, Mr. Biden would have an opportunity to try to blunt Mr. Trump’s charges that the former vice president is “senile” and “sleepy,” just as John F. Kennedy countered Richard Nixon’s claims that he was too young and inexperienced to assume the presidency in 1960. 

In the potential absence of these traditional events, Mr. Biden will need to be creative in how he engages voters, says Mr. Shrum. And his vice presidential pick will likely carry even more weight – not only because of Mr. Biden’s age, but also because of the absence of other high-profile campaign moments.

Above all, say several strategists, Mr. Biden needs to try to stay in the public eye as he has over the past week, and propose policies that follow through on his promise to bring unity.

“Part of [Mr. Trump’s] strategy will be to undermine voters’ confidence in Joe Biden,” says Monmouth’s Mr. Murray. “That’s why Biden has to be out there – so he can change people’s minds from ‘I think he can do a good job’ to ‘I know he can do a good job.’”

At the same time, Mr. Biden has made a point throughout the campaign of keeping the focus less on himself and more on the country.

In 2019, Mr. Biden’s campaign announcement video was centered on Charlottesville, Virginia, where two years earlier white supremacists had shocked the nation as they marched with tiki torches. In the video, Mr. Biden referenced Mr. Trump’s response to the event as a key moment that pushed him to run for president. 

“We are in a battle for the soul of this nation,” he said. “We can’t forget what happened in Charlottesville. Even more important, we have to remember who we are.” 

“I see Joe responding in a way that reflects who he’s always been,” says Senator Coons. “It’s not about him. It’s about us.”

Note: An earlier version of this story referred to “Washington police” as having cleared protesters from Lafayette Square. The story has been updated to make clear it was U.S. Park Police in Washington.