After taking command of the Democratic nominating race in Tuesday's primaries, the former vice president projected presidential-style gravitas, positioning himself as the antidote to President Donald Trump's in-denial stewardship of the novel coronavirus crisis in a strategic pivot towards November's election.

Biden's move at this particular moment is a sign of just how much the pandemic's arrival on US shores has transformed the political environment and the terrain of the 2020 election in a way that may soon mirror wrenching changes coming to everyday American life.

In a short televised speech Tuesday night, Biden offered a preview of orthodox, conventional leadership the country has not seen in the three years of Trump's sledgehammer presidency. The election that takes place in the wake of the Covid-19 pandemic may test whether enough Americans, traumatized by a national crisis, want that return to "normal" or will decide to stick with Trump's tear-it-down leadership.

"At this moment, when there's so much fear in the country and so much fear across the world, we need American leadership," Biden said in a sober tone, with his wife Jill by his side.

"We need presidential leadership that's honest, trusted, truthful and steady, reassuring leadership," Biden added.

"If I am given the honor of becoming your president, I promise you, I'll strive to give the nation that very leadership every day, every day, I have the privilege to hold office."

Biden's new strategic approach comes with risks. He could antagonize Sanders supporters if he is seen as presumptuous and seems to be pushing the Vermont senator out of the race. And it is likely to bring down the full force of Trump's political and propaganda machine on a campaign that until a few weeks ago struggled to parry incoming attacks.

Biden spoke shortly before the number of confirmed cases of novel coronavirus in the United States breached the 1,000 barrier -- doubling since Sunday. He said he would make an address later this week on how to respond to the virus threat.

He appeared only hours after Trump gave his latest update on a pandemic that he has sought to minimize while accusing Democrats of using his response to it as a "hoax" to damage him politically.

"We're prepared, and we're doing a great job with it. And it will go away. Just stay calm. It will go away," Trump said after meeting Republican senators on Capitol Hill.

The President's instinct to downplay the coronavirus threat represents a wager with his presidency less than eight months before Election Day.

Reports of confusion and shortfalls in testing kits for suspected coronavirus patients, school closures, the isolation of a community in New York state, stock market slumps and a looming disaster in the suddenly passenger-deprived airline industry have all failed to shake Trump's insouciance.

Biden, who has watched multiple presidents handle national crises since coming to Washington as a young senator nearly half a century ago, understands how to play the role he thinks that Americans are pining for. His bet is that after two previous failed campaigns, the political demands of the moment might finally be lining up for a competent Washington veteran who peddles the kind of empathy that the current President lacks.

One Biden adviser told CNN's Jeff Zeleny that Biden wanted to turn to a more "presidential footing" and planned to start giving speeches about "the gravity of the moment."

Risks to Biden's approach

But the approach brings political risks. First, any impression that the former vice president is trying to hound Sanders out of the race could inflame the democratic socialist's supporters.

That is why Biden, while speaking of his old Senate colleague as if he had already folded his campaign, styled him as a partner rather than a rival in his remarks in Philadelphia.

"I want to thank Bernie Sanders and his supporters for their tireless energy and passion. We share a common goal. Together we'll defeat Donald Trump. We'll defeat him together. We'll bring this nation together," Biden said.

If Biden continues to expand his delegate lead and takes the Democratic nomination, he knows that his chances of beating Trump in November could splinter without the backing of Sanders.

The changed circumstances of the race following Biden's comeback in South Carolina and his Super Tuesday romp, as well as the current public health emergency, leave Sanders with difficult choices.

Does he stay in the race and continue to tear strips from an opponent who could be the party's eventual nominee -- even at the risk of helping Trump? Or does the Vermont senator remain a candidate but tone down his attacks on Biden -- including at Sunday's CNN debate in Arizona -- but turn his fire on Trump?

Or does the prospect of a likely string of defeats to Biden in the next few weeks risk damaging Sanders' leverage and credibility with his Democratic colleagues and lead him to fold his campaign while preserving the mystique of his movement?

All of these agonizing choices will be rendered even more complicated by the sensitive political moment conjured by the coronavirus pandemic and fast rising rate of infections in the US.

With public anxiety mounting, there may be little tolerance for a Sanders campaign that could come to be seen as self-indulgent if there is no real possibility he could catch Biden in delegates.

And after also canceling his election night rally in Ohio, Sanders faces an unpleasant reality: if he can't stage his huge rallies with thousands of supporters, how is he going to fire up his political base and pull off an unlikely comeback?

Biden is about to incur Trump's wrath

Biden's new presidential posturing is also likely to antagonize Trump. After all, as the Obama administration used to remind the team of the former real estate magnate and 2016 president-elect, there is only one president at a time. Biden has no real power -- as not yet even the party's presumptive nominee -- to influence the course of the nation's response to the coronavirus epidemic.

And while Trump has often been absent and peddled falsehoods and political attacks during the crisis, his Vice President Mike Pence has been winning high marks -- even among some Capitol Hill Democrats -- for his efforts to provide leadership.

Any impression that Biden is exploiting the situation for his own political ends could backfire. And if the pandemic's impact on the US is as dire as some experts predict, media coverage may quickly move away from a candidate pretending to be president.

Conservative media, including Fox News commentators, spent the evening upping their attacks on the man that will increasingly be seen as the President's likely opponent in November.

Biden will be under intense pressure in the days ahead to avoid the kind of gaffes and verbal miscues that have marked his career and enable Trump's media cheerleaders on the right to portray him as bumbling and past his prime.

Trump's Senate allies are likely to respond to his success in the Democratic primary by expanding their efforts to investigate Biden. And the President's campaign is a well-funded, skillful and ruthless outlet bristling for the chance to bring Biden down.

Still, the former vice president is hardly going to be surprised at the incoming fire. After all, Trump's previous attempts to nobble him -- over his son Hunter's business ventures in Ukraine -- led to the President's impeachment. He does however need to find a more convincing way to respond to such attacks if he's not going to get into trouble against Trump in the fall.

And Biden appears to believe that his campaign could benefit from a case of cometh the hour, cometh the man.

"It means replacing a President who demeans and demonizes people with a president who believes in empathy, compassion and respect for everyone," he said.