The oppressive silence that greeted the masked pair -- so different from the palm-slapping and hugs on which Biden thrived when unveiled as Barack Obama's running mate 12 years ago -- underscored the disorienting nature of the most unusual campaign in history and the national crisis that has frozen normal life.
Biden and Harris essentially offered a return to a traditional, conventional vision of the presidency, pledging competence, empathy, hope, diversity, unity and sober leadership at a grave moment. The California senator also appeared especially adept in filleting Trump's handling of the pandemic and the consequent economic crash on a day when around 1,400 more Americans died.
"This virus has impacted almost every country but there's a reason it has hit America worse than any other advanced nation. It's because of Trump's failure to take it seriously from the start -- his refusal to get testing up and running, his flip-flopping on social distancing and wearing masks, his delusional belief that he knows better than the experts," Harris said.
"All of that is the reason that an American dies of Covid-19 every 80 seconds. It's why countless businesses have had to shut their doors for good," said Harris in the most effective election-year critique yet of Trump's performance. "Trump is also the reason millions of Americans are now unemployed."
Watching on, Biden could savor his best day since pulling off the campaign-saving win in the South Carolina primary, eons ago in the pre-Covid world, that rescued his faltering presidential dreams.
A rambling President
In the second half of Wednesday's previews of the online and watered-down party conventions in the next few weeks, Trump was nowhere near his best political form. While Biden and Harris were energized at the start of their journey, Trump, shoulders hunched, alone at the podium, seemed exhausted and even incoherent at times.
He made the politically off-key choice to begin the briefing with charts showing US stock market performance compared to foreign nations -- as if soaring equities compensated for the economic pain of millions of unemployed.
"I didn't print those charts," Trump said, bizarrely, at one point. "We took those numbers from somebody."
A comment about the virus-threatened college football season was similarly incoherent and he twice mispronounced the word fatalities as "fatilities." Such slips might not normally matter, but Trump has been excoriating Biden for what he says are his decaying mental faculties.
While Trump ostensibly was supposed to be briefing Americans about the pandemic -- and helping his own political prospects in the process -- Wednesday's briefing didn't appear to accomplish either goal. The President ran his usual routine of false narratives about the virus, littered with untrue claims of great success, misinformation about testing and showed no empathy to victims, while grousing about his press coverage.
He renewed his push for schools to open come what may -- ignoring the alarming rise of coronavirus infections among kids -- and the fact that they could transmit the disease to more vulnerable parents and grandparents. His omission was especially jarring since some schools in several states that have taken his advice now have hundreds of students and staff quarantined.
This was far from the rambunctious, outrageous and energetic political destroyer who squelched a golden generation of Republican presidential hopefuls and pulled off the greatest political upset in history in 2016.
And if, as seems likely, the 2020 election is to be conducted on television in front of sparse crowds of reporters, socially distanced, the evidence of Wednesday suggests that Trump will be at a significant disadvantage.
The attempt by Biden and Harris to promote themselves as the caring, competent answer America needs in a dark hour is actually helped by their liberation from the need to hit applause lines to whip a crowd into a frenzy.
But Trump's political appeal is best appreciated as he sucks energy from an adoring crowd, that relishes his slaying of political correctness and eggs him on to greater improprieties that exemplify his appeal as a scourge of the establishment and the voice of "deplorables" who feel scorned by self-appointed "elites."
After the President said he wouldn't do events before empty arena seats in the age of Covid-19, he must be contemplating the unappealing possibility that he may have already romped through the last of the rallies that defined his political persona.
Both sides fight to define the election
An objective viewer who missed the tumult of the Trump presidency and the furious politics unleashed by the pandemic might conclude after observing Wednesday afternoon unfold, that Biden and Harris are on the road to victory -- if the election is defined by the worst public health crisis in 100 years.
But there is no such binary choice on the ballot on November 3 as much as Democrats would like that to be the case. There can be few voters left after three-and-a-half years that have shattered national unity who have an objective view of Trump, the most divisive president in modern history.
Trump's populist nationalism, rule breaking and worldview that sees America ripped off by enemies and allies alike is a good fit for how they actually feel -- whatever they might think about a pandemic that he already claims to have conquered.
Betting that they know the national mood better than Democrats and the media, Trump and his team are trying to turn the election away from the pandemic into a culture clash, leveraging issues of race and public order to portray Biden and Harris as avatars of an extreme liberalism that will lead to carnage in the cities and the destruction of the fabric of traditional (White) American life. That warning is encapsulated by Trump's conjuring of an influx of low-income minority residents that will alarm "the suburban housewife" much as he stigmatized Mexican immigrants during his first presidential campaign.
The President's attempts to discredit mail-in voting -- even in the midst of a pandemic -- might be an attempt to explain away a possible loss, but also appear to be an attempt to suppress the diverse "Obama coalition" vote that Biden and Harris were so obviously targeting in the roll-out event on Wednesday.
Perhaps the most significant aspect of the performance by Harris, highlighted by eloquence and ease of long-rising star who is now genuinely a top Democratic power player, is that it appeared to defuse Trump's racially suggestive attacks that she is mean, "nasty" and "angry" and "mad."
Democrats who have been longing for a ray of hope since Obama departed the White House can barely have hoped for such a smooth and effective debut of their presidential ticket. The President's team have seemed oddly off their game in the crucial first attempts to define the vice presidential nominee.
But there will be tougher days ahead for currently euphoric Democrats, and Trump and a well funded campaign that is prepared to do anything to win are unlikely to always be as unfocused and dispirited as the President appeared to be on Wednesday.