President Donald Trump tore into his election challenger Joe Biden as a threat to the "American Dream" in a bruising speech Thursday accepting the Republican nomination for a second term against a backdrop of racial tensions and the deadly coronavirus pandemic.

The former celebrity real estate developer spoke at a grandiose event staged at the White House -- the first time a president has ever held a party convention at the executive mansion -- and followed up with a vast fireworks display on the National Mall.

In his 70-minute address, Trump went after Biden as hard as he could, attacking him by name dozens of times in an attempt to define the veteran centrist former vice president, who leads in polls ahead of the November 3 election, as a radical leftist.

"No one will be safe in Biden's America," he said.

"This election will decide whether we save the American Dream," Trump said, rejecting Biden's main campaign slogan about saving America's soul.

"He's the destroyer of America's jobs and given the chance, he'll be the destroyer of American greatness."

The relentless verbal assault contrasted with Biden's own acceptance speech at the Democratic nomination last week, which lasted only 25 minutes and, while delivering caustic critiques of the Trump presidency, avoided mentioning his name.

Despite Trump's warnings of chaos, his bid for reelection is already taking place amid levels of turmoil the country hasn't seen for decades.

Covid-19 has killed more than 180,000 Americans so far, while the nation's painful reckoning over racial justice was playing out outside the White House where a Black Lives Matter protest, complete with shouting and vuvuzela trumpets, was audible inside the fences.

Trampling over etiquette

Trump spoke from the White House's South Lawn, which he had transformed into a flashy event center for the final night of the Republican convention.

Trampling over long-running presidential custom to separate the so-called "people's house" from political campaigning, Trump had some 1,500 white chairs laid out in front of the stage bedecked with rows of US flags and two giant video screens.

The immense fireworks displayed featured Trump's name written in fiery letters in the sky.

Before Trump appeared from the White House in a made-for-Hollywood moment alongside his wife Melania, warm-up speakers including his powerful daughter Ivanka prepped the message of Democratic mayhem.

And when Trump finally came to deliver the main speech, he did not hold back.

"If the left gains power, they will demolish the suburbs, confiscate your guns," he said, branding Biden as a man with a history of "betrayals" and "blunders."

Republican strategist Matt Mackowiak said the party had hit the right buttons at its four-day convention. "Trump significantly broadened his coalition this week. He will get a considerable polling bump," he tweeted.

But Biden mocked Trump's apocalyptic warnings.

"When Donald Trump says tonight you won't be safe in Joe Biden's America, look around and ask yourself: How safe do you feel in Donald Trump's America?" Biden tweeted.

Law and order?

The hardline message comes as the country reels in shock at the videotaped shooting by a police officer of an African American man during an attempted arrest in front of his children -- and at the sometimes violent protests erupting afterward.

Days of demonstrations and rioting in Kenosha, Wisconsin, have transformed the small town into a national arena for America's tensions over racial justice, police violence, and gun rights. When a teenaged vigilante -- reportedly a Trump fan -- allegedly killed two people and seriously wounded a third at a protest Tuesday night, the perfect storm was complete.

Struggling in opinion polls after what almost two thirds of Americans say is his unsatisfactory handling of the Covid-19 crisis, Trump is latching on to what he calls the "law and order" strategy.

Democrats assert that police forces across the country are plagued by institutional racism. Trump is leading Republican pushback, banking on the idea that Americans will be angrier at scenes of rioting than at police abuses.

"If Biden is elected, along with the Democrats who are unwilling to speak out against this anarchy, then the crime wave will intensify and spread from cities and towns to suburbs and beyond," Rudy Giuliani, the former New York mayor and current personal lawyer to Trump, said in his warm-up speech.

"When President Trump is re-elected the damage will stop," he said.

Milking the violence?

In addition to soaring racial tensions, the United States is still struggling to master the coronavirus outbreak or get schools and businesses back fully open.

But Trump emphasized what he said had been his administration's constant success, predicting a vaccine would be available "this year."

"Together we will crush the virus," he said.

At the Republicans' South Lawn party, there was no effort to enforce social distancing and many people did not wear masks.

Biden's team accuses Trump of being derelict on the coronavirus. On the race front, Biden goes further.

"He views this as a political benefit to him," Biden told MSNBC on Thursday. "He is rooting for more violence, not less. He is pouring gasoline on the fire."