US President Donald Trump speaks from the South Lawn of the White House on the fourth day of the Republican National Convention, in Washington, Aug 27, 2020. (EVAN VUCCI / AP)

WASHINGTON - A defiant US President Donald Trump accepted the Republican nomination for a second term on Thursday with a scathing attack on rival Joe Biden, asserting that a Democratic victory in November would only exacerbate the racial strife and coronavirus pandemic besieging the nation.

Speaking from the White House South Lawn despite criticism he was using the executive residence as a political prop, Trump portrayed Biden, a career politician with a long record as a moderate, as a far-left extremist who would usher in a lawless, dangerous America.

This election will decide whether we protect law-abiding Americans, or whether we give free rein to violent anarchic agitators and criminals who threaten our citizens. 

Donald Trump, US president

"This election will decide whether we protect law-abiding Americans, or whether we give free rein to violent anarchic agitators and criminals who threaten our citizens," Trump said on the fourth and final night of the Republican National Convention in a rambling speech that lasted more than an hour.

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

Despite the pandemic that has killed more than 180,000 Americans, Trump delivered his remarks before a crowd of more than 1,000 people, standing in front of dozens of American flags and basking in chants of "Four more years!" and "U.S.A.!"

His language was evocative of his 2016 convention acceptance speech, which also came at a time of racial tension after eight police officers were killed in Texas and Louisiana amid protests following shootings of Black men.

"Americans watching this address tonight have seen the recent images of violence in our streets and the chaos in our communities," he said then, vowing to end the turmoil.

But Trump, who ran successfully as an insurgent four years ago, is now in control at the White House, complicating his assertion once again that only he can solve the problem.

Republicans on Thursday sought to advance that message after days of civil unrest and violence in Kenosha, Wisconsin, where on Sunday police shot a Black man, Jacob Blake. They inaccurately asserted that Biden would "defund the police." Biden has rejected that position. 

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In trying to paint Biden as a tool of the "radical left," Trump also distorted the Democrat's policy positions on a host of other issues, including immigration, guns, law enforcement, abortion and energy production

As the night unfolded, Biden struck back on Twitter, writing, "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?"

In trying to paint Biden as a tool of the "radical left," Trump also distorted the Democrat's policy positions on a host of other issues, including immigration, guns, law enforcement, abortion and energy production.

"If given the chance, he will be the destroyer of American greatness," Trump warned.

The made-for-television scene - befitting the first reality TV host to serve as president - stood in marked contrast to Biden's acceptance speech last week, which was broadcast live from a largely empty arena in a nod to the disease.

Following the speech, fireworks exploded over the Washington Monument as the president and his family looked on, giving Trump and the convention a powerful closing image.

The crowd, seated in white chairs inches apart, showed little evidence of social distancing or face masks despite health experts' recommendations. But the Trump campaign said it had taken appropriate health precautions in arranging the South Lawn event.

In a reminder of the country's divisions, attendees could hear anti-Trump protesters at nearby Black Lives Matter Plaza as he spoke.

Shifting blame

Trump, a former New York real estate developer, is seeking to turn around a re-election campaign that has been largely overshadowed by a health crisis that has put millions of Americans out of work and killed more people than in any other country.

His campaign also comes against the backdrop of a fresh wave of protests over the latest high-profile police shooting of a Black American. In Kenosha, relative calm returned after three nights of civil strife ending on Tuesday, including arson, vandalism and deadly shootings.

Trump promised to rebuild what Republicans have called the "greatest economy" in history

He also promised to rebuild what Republicans have called the "greatest economy" in history and attacked Biden for saying he would shut down the country if necessary to slow the spread of the disease. Many health experts blame a resurgence of coronavirus cases on states that reopened businesses too soon.

"Joe Biden's plan is not a solution to the virus, but rather a surrender," Trump said.

While his approval rating among Republican voters remains high, dissent is mounting within the party. In three open letters being published on Thursday and Friday, Biden won endorsements from more than 160 people who worked for Republican former President George W. Bush or for past Republican presidential candidates Mitt Romney and John McCain, the New York Times and Politico reported.

Earlier this week, 27 former Republican lawmakers endorsed Biden while the Lincoln Project, among the most prominent Republican-backed groups opposing Trump, said a former Republican Party head had joined it as a senior adviser.

READ MORE: Biden promises 'light' over 'darkness', warns against Trump

While Trump's approval rating among Republican voters remains high, dissent is mounting within the party. Biden won endorsements from more than 160 people who worked for Republican former President George W. Bush or for past Republican presidential candidates Mitt Romney and John McCain, the New York Times and Politico reported

Thursday's program aimed to counterbalance those defections, featuring a video showcasing former Democratic voters who say they now support Trump and remarks from US Representative Jeff Van Drew, who abandoned the Democratic Party to join the Republicans after voting against Trump's impeachment this year.

"Joe Biden is being told what to do by the radicals running my former party, the same radicals trying to install him as their puppet president," he said.

The program also included several emotional appeals, including from the parents of Kayla Mueller, an aid worker who died after being held captive for months by Islamic State militants in Syria. The Mueller parents said they blamed the Obama administration for failing to rescue Mueller.     

Trump kicked off the week on Monday by accusing Democrats of seeking to steal the election by advocating for mail-in voting.

His previous high-profile speeches have also emphasized grim themes, including his inaugural address in January 2017 that described "American carnage."

With both parties' conventions now complete, the campaign will enter its final, frenetic stretch. Biden, who has largely eschewed in-person events since March because of the pandemic, said at a Thursday fundraiser he expects to travel to several battleground states after early September, albeit in a manner he described as responsible.

Trump, who has visited several battleground states during the pandemic, also plans to increase his campaign travel.