Cratering in the polls, canceling his showcase convention event, and struggling to land punches on his opponent, Donald Trump has only 100 days from Sunday to save his presidency -- and it's not going well.

In the latest blow to momentum ahead of November 3, the president announced late Thursday that he was ditching the razzmatazz-filled Republican convention in Florida for next month because of coronavirus fears.

An indication of how badly Trump wanted the made-for-TV affair in Jacksonville, complete with screaming crowds, warm-up acts and constant adulation, is that he'd moved it to Florida when coronavirus fears had already scotched his original plans for North Carolina.

"It's a different world," Trump said.

Coronavirus has not only upset Trump's pageant. The disease is ravaging the US economy, adding steadily to a death toll of well over 140,000, and undermining public confidence in government.

Add explosive protests against racism and police brutality, leftist-led riots, flourishing right-wing conspiracy theories, and the specter of Russian meddling -- and you have a country more on edge than at any time since the cataclysmic 1960s.

Now Trump, who boasts he never tires of "winning," faces possible humiliation at the hands of Democrat Joe Biden, a man he derides as "sleepy" and mentally incompetent, yet who leads by double digits in some polls.

In 2020, a year of historic uprisings against racism and sexism in the United States, the match-up between Trump, 74, and Biden, 77, might seem out of step. 

One is a billionaire born into extreme privilege, while the other, with three decades in the Senate and two terms as vice president under Barack Obama, is the epitome of the professional politician.

Yet Trump vs Biden will deliver all the upheaval a confused and bitter US electorate can stomach.

Trump's pitch boils down to claiming Biden will have Americans "cowering to radical left-wing mobs."

Biden, no less apocalyptic, says he's fighting for "the soul of America."

Down but not out 

Polls give Biden an advantage nationally, strong leads in swing states, and even a shot at Republican strongholds like Texas. Congressional Democrats, who already control the House, are eying recapture of the Senate.

Trump presides over mass unemployment -- even if this was triggered by the coronavirus shutdown -- racial unrest and a growing crisis of confidence. On the pandemic, the biggest issue of the day, polls show that two-thirds of Americans have no faith in his leadership.

To boot, Trump, with overall approval ratings permanently stuck in the low 40 percent range, is the first president to seek reelection after impeachment.

Yet no one counts him out.

Belittled as a clown in 2016, he handily defeated all the top Republican establishment names for the nomination. He then came from behind to defeat the Democrats' polished candidate Hillary Clinton.

Trump believes he still has the secret sauce.

"I'm not losing, because those are fake polls," he insisted on Fox News last weekend. "They were fake in 2016 and now they're even more fake."

Two 'invisible' enemies 

COVID-19, which Trump calls "the invisible enemy," makes a frustrating target for a man used to dealing in large, tangible objects, like skyscrapers.

But he's having an equally hard a time getting to grips with Biden.

The Democrat is running a unique campaign from his Delaware home, with no rallies, few media interviews and even rarer press conferences.

This began with social distancing but has grown into what critics mock as the "bunker strategy" -- and an extraordinarily lucky boost for a candidate widely seen as a gaffe machine.

Rather than take risks, Biden is able to sit back, ignore the #HidenBiden hashtag jibes, and watch Trump lurch ever deeper into his own self-inflicted troubles.

Trump campaign spokesman Hogan Gidley said Friday that voter enthusiasm will make the difference at the polls.

"Our supporters will stand through rain, sleet, snow, hail, and crawl across broken glass to vote for Donald Trump," he told Fox News' "Fox & Friends" show. "Joe Biden's supporters won't even click on a link to watch him doing a Q&A."

'Death star' 

That has long been team Trump's theory -- that their man has a unique ability to fire up the base.

But Brad Parscale, the once uber-confident campaign manager who described the campaign as the "Death Star" from the "Star Wars" movies, has been demoted. And the vaunted reelection machine now resembles a misfiring rocket.

Trump's mass rallies, vital to his political identity, have fizzled due to health risks, while his trademark bravado and name-calling sits less easily in a country shaken by death and economic misery.

Cornered, Trump is doubling down with fearmongering. It's a vision of chaos, violent crime and what Trump tweeted is Biden's desire to "abolish the American Way of Life."

Come November 3, coronavirus precautions and mail-in ballot use will complicate voting, meaning late tallies. Last week, Trump repeated his claim that efforts are underway to "rig the election."

Then he went further.

Asked on Fox News if he would accept the results, as every president before him has, Trump said this:

"I have to see."