Joe Biden, standing in an empty convention hall in Delaware, warned that there's no miracle cure for the coronavirus pandemic that has killed more than 180,000 Americans on President Donald Trump's watch. The Democratic presidential nominee, offering solace to a suffering nation, said "decency, science, democracy, they're all on the ballot."

Trump, hosting a packed GOP convention crowd on the White House South Lawn, told of another apocalyptic future — one without law and order, where Democrats would give "violent anarchists and agitators and criminals" free rein over the country.

The back-to-back party conventions painted a dark picture of a divided nation and set the stage for a presidential race that portends an epic clash between Republicans promising to restore order and Democrats vowing to restore a semblance of normalcy.

In words and images, the unprecedented virtual gatherings also provided sharply contrasting perspectives on a summer of urban unrest as the nation comes to terms with episodes of disturbing police violence against Black men in Minnesota and Wisconsin, both in the heart of the Midwestern battleground.

For both sides, the stakes couldn't be clearer.

"They always say that every four years, every election is the most important election since the last one, but I think both sides believe it more deeply than usual," said David Sturrock, a former Minnesota Republican Party officer and a political-science professor at Southwest Minnesota State University.

Ushering forth two well-known nominees in Trump and Biden, the parties kicked off their fall campaigns in somber, existential framing for the Nov. 3 election. For Democrats, that meant appeals to social justice and tapping into polling that shows broad dissatisfaction with the administration's handling of the pandemic.

The Republicans' focus on law and order relegated the pandemic to the background, hardly noticeable in the sea of maskless faces coming together for Trump's in-person acceptance speech on the White House grounds. The event infuriated Democrats and some conservatives who called it an improper — and possibly illegal — political use of government property.

"Get off our lawn," tweeted Minnesota U.S. Sen. Amy Klobuchar, a former contender for the Democratic nomination.

Trump reveled in the stately backdrop of the White House, the sort of break from political tradition that delights his followers: "We are here," he said, "and they are not."

Trump's unapologetic appropriation of the White House, and the National Mall fireworks display that went with it, gave Republicans the sort of patriotic spectacle that animates their America First base. For Democrats, it played into one of their central arguments for his ouster.

"The message was, in part, are you tired of this [expletive] show? Are you tired of all of this?" said Norman Ornstein, Minnesotan and resident scholar at the American Enterprise Institute in Washington, D.C. "We can go back to some semblance of normality with Biden."

Republicans centered their message on the riots, looting and destruction across the country, counting on the disorder in Minneapolis and other cities to bring suburban voters into the Republican fold, whatever their reservations about Trump.

Speakers disavowed "cancel culture" and "Woketopians," framing socialism and anarchy as the greatest threat to the American way of life. Mark and Patty McCloskey, who were charged for allegedly waving their guns as Black Lives Matter protesters marched past their home in St. Louis, warned that the same thing could happen to others "watching from quiet neighborhoods" across the country.

"It's almost like this election is shaping up to be church, work and school, versus rioting, looting and vandalism," said Donald Trump Jr., the president's son, on the opening night of the Republican National Convention.

While Democrats promised to address racial inequities, voters of color featured in the Republican convention vouched for the Trump administration and policies they say led to record employment — at least before the virus hit.

"The Republicans know they're not going to pull over a significant portion of Black voters, so part of that messaging is to moderate whites saying, 'Look, our party, we're not racist,' " said Michael Minta, a political-science professor at the University of Minnesota who focuses on race and ethnicity. "They're saying, 'How could this guy be racist if he has these people who are vouching for him and his credibility and integrity?' "

Even as the Minneapolis police killing of George Floyd infused a new racial subtext into election-year politics, Minnesotans weren't featured prominently in either convention. Klobuchar scored a speaking slot on the opening night of the Democratic convention. She talked about unity and the right to vote. Republicans tapped Eveleth Mayor Bob Vlaisavljevich, a former Democrat who praised Trump's support for the mining industry, the lifeblood of the Iron Range, where Republicans see a bounty of rural white voters.

For the broader public, conventions are a signal to start tuning in to the campaigns. For each party's base, it's a way to rev up its most active members, who typically mingle with their peers in the convention halls and return home and start on the groundwork of campaigning.

"There's a certain organizational element to the conventions that helps," said Vin Weber, a lobbyist and former Republican congressman from Minnesota. "That's missing, you can't do that virtually."

Millions of Americans, held captive in their homes by the pandemic restrictions, still tuned in to the two surprisingly glitch-free virtual conventions. Some pundits note that the ongoing pandemic, the waves of civil unrest and the deepening polarization of politics have done much of the work of motivating voters this year.

"Emotions are high given everything that's going on, and it's also about how polarized we've become," said Ben Toff, an assistant professor at the University of Minnesota's journalism school, who also works at the Center for the Study of Political Psychology. "It's not just an intellectual debate about policy, and frankly, there hasn't been a lot of policy discussion in these conventions. It's been about identity. Those emotions are very much at the surface."

Briana Bierschbach • 651-925-5042

Twitter: @bbierschbach