Joe Biden takes to the biggest stage of his life Thursday with a speech accepting the Democratic nomination for the White House in which he will promise a divided, traumatised nation a "new path" if he defeats President Donald Trump.

Speaking in his hometown of Wilmington, Delaware, but with an audience almost entirely online or on television, Biden's acceptance speech reflects the enormity of the shutdown that has upended life across the United States in the battle against the deadly coronavirus.

Democratic presidential nominee Joe Biden
Democratic presidential nominee Joe Biden is set to deliver his acceptance speech at the Democratic National Convention. Photo: AFP / Olivier DOULIERY

And Biden is urging Americans to punish Trump for the chaos.

"Donald Trump is not responsible for COVID-19, but he does bear full responsibility for the failed national response," Biden said ahead of his live television speech wrapping up the Democratic convention.

Democratic vice presidential candidate Kamala Harris
Democratic vice presidential candidate Kamala Harris is the first black woman on a major party ticket. Photo: AFP / Olivier DOULIERY

"We've got to hold him accountable this November," the 77-year-old former vice president under Barack Obama and long-time senator from Delaware tweeted.

Biden -- on his third White House bid after failing to win the nomination in 1988 and 2008 -- said he will expand on his plans to "build back better and set this nation on a new path."

US President Donald Trump
US President Donald Trump is to deliver remarks in Pennsylvania, near his Democratic opponent Joe Biden's hometown. Photo: GETTY IMAGES / CHIP SOMODEVILLA

Biden leads in almost every national opinion poll, and in most of those in the swing states.

Kamala Harris and Joe Biden
IMAGES AND SOUNDBITESKamala Harris makes history as she accepts the Democratic Party's nomination for vice president in Wilmington, Delaware, becoming the first Black woman to run on a major party's presidential ticket. "I pledge to you that we will act boldly and deal with our challenges honestly," Harris says in her acceptance speech. Photo: DC POOL

But in a reminder of how hard Trump intends to fight, he tried to steal Biden's thunder earlier Thursday with a visit just outside his challenger's birthplace in Scranton, Pennsylvania.

In a remarkably dark speech, Trump falsely claimed that Biden had abandoned the blue collar town -- he in fact moved out with his family when he was a child -- and warned that Democrats would usher in an era of "violent mobs" and "blood-stained sidewalks."

Support in percent for Joe Biden, Trump
Support in percent for Joe Biden and Donald Trump, according to Real Clear Politics' national poll average. Photo: AFP / Gal ROMA

Pennsylvania is exactly the kind of place that used to be reliably Democratic but has now divided, with many seduced by Trump's economic nationalism and vows to defend traditional white, working class values. The state will be fiercely contested on November 3.

The Democratic convention, however, has demonstrated that Trump faces a more united foe than in 2016.

He is also weighed down, as throughout his first term, by ever more distractions and scandals, the latest being Thursday's arrest of his 2016 campaign manager Steve Bannon for alleged fraud.

In more bad news for Trump, a New York judge rejected the president's bid to block the release of his financial records to the Manhattan district attorney in another inquiry.

Biden's acceptance speech will be the final salvo in a convention that was originally planned to take place with the usual big crowds in the battleground state of Wisconsin.

The Democrats have responded to the online challenge with a flurry of speakers giving shorter speeches, sprinkled with musical acts and highly produced videos.

Emphasizing their unity, other speakers on Thursday include politicians who had challenged Biden for the party's nomination -- former South Bend, Indiana, mayor Pete Buttigieg, New York billionaire Michael Bloomberg, entrepreneur Andrew Yang and New Jersey Senator Cory Booker.

On Wednesday, it was the turn of Kamala Harris to accept the vice presidential nomination, making her the first black woman ever to make it onto the White House ticket of a major party.

"Donald Trump's failure of leadership has cost lives and livelihoods," Harris said. "We're at an inflection point."

Other big names to speak -- and to launch withering attacks against Trump -- include Obama and his popular wife Michelle Obama.

On handing over the White House to Trump in 2017, Obama said he thought the Republican "might show some interest in taking the job seriously; that he might come to feel the weight of the office and discover some reverence for the democracy that had been placed in his care."

"But he never did," the former president said.

Trump has left America's "worst impulses unleashed, our proud reputation around the world badly diminished, and our democratic institutions threatened like never before," Obama said.

Trump responded by telling reporters that Obama had been "a terrible president."

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