WILMINGTON, DELAWARE (AFP, REUTERS) - Democratic White House hopeful Joe Biden on Wednesday (Aug 12) introduced his vice-presidential candidate Kamala Harris at their first joint appearance as an inspiring woman who would help him to "rebuild this country."

Accusing United States President Donald Trump of failing to lead during the coronavirus crisis, Mr Biden said that he and Ms Harris would fix "the mess that President Trump and Vice-President Pence have created at home and abroad".

The Democrat, who walked out with Ms Harris onto the stage in his hometown of Delaware, said her historic role as only the third woman ever picked for the vice-presidency by a major party was inspiring "little girls" across America.

Mr Biden praised Ms Harris as an experienced and accomplished governing partner who would help him deliver on his campaign agenda.

"I have no doubt that I picked the right person to join me as the next vice-president of the United States of America, and that is Senator Kamala Harris," Mr Biden said in introducing Ms Harris, who sat behind him on stage during his speech.

"She's ready to do this job on day one. We're both ready to get to work rebuilding this nation," he said.

Ms Harris said Mr Biden, the former vice-president under President Barack Obama, had recognised the critical moment being faced by the country by picking her to be the first black woman and Asian American on a major-party US presidential ticket.

"Today, he takes his place in the ongoing story of America's march toward equality and justice as the only person who served alongside the first black president, and has chosen the first black woman as his running mate," said Ms Harris, a US senator from California.

Nearly nine out of 10 Democrats approved of Ms Harris as Mr Biden's pick, according to a Reuters/Ipsos poll released on Wednesday.

Forced by the coronavirus pandemic to stage a more subdued launch than would be expected from a typical presidential campaign, the new running mates managed to display a personal connection that dates back to Ms Harris' friendship with Mr Biden's son Beau, who died of cancer in 2015.

Ms Harris said she had long admired Mr Biden's commitment to his family and country, and she described him as ready to meet the challenges created by Mr Trump's failures in handling the pandemic and its economic consequences, as well as racial unrest.

"This is a moment of real consequence for America," she said. "Everything we care about - our economy, our health, our kids, the kind of country we live in - it's all on the line.

"America is crying out for leadership, yet we have a president who cares more about himself than the people who elected him, a president who is making every challenge we face even more difficult to solve," she said.

The joint appearance came just days before Mr Biden will formally accept the Democratic presidential nomination at next week's party convention, which will take place largely as a virtual event because of the coronavirus pandemic.

The Republican convention, where Mr Trump is set to be nominated to seek a second four-year term, follows a week later and kicks off a 10-week sprint to the Nov 3 election.

Ms Harris, the 55-year-old US senator from California, was announced as Mr Biden's choice on Tuesday after a selection process that drew extra scrutiny thanks to Mr Biden's age.

The 77-year-old would be the oldest president ever if he wins, raising speculation that he would not seek re-election in 2024.

Ms Harris is the daughter of two immigrants - her mother is from India and her father from Jamaica.

Wednesday's event in Mr Biden's East Coast hometown took place on the third anniversary of the "Unite the Right" rally in Charlottesville, Virginia, where violent clashes erupted as white supremacists and neo-Nazis descended on the town.

Mr Biden has said Mr Trump's comment after the clashes that there were "very fine people on both sides" - which drew widespread criticism - convinced him to run for president.

In recent months, as unrest has convulsed many US cities following the May police killing of Mr George Floyd, a black man in Minneapolis, Ms Harris has become a prominent voice calling for change. She has marched alongside protesters and pushed legislation to reform policing practices.

A crowd of about 75 people gathered outside in a light rain before the event to get a glimpse of Mr Biden and Ms Harris, holding signs and snapping pictures. Most were supporters and some chanted Ms Harris' name, although some were Biden opponents.

In choosing Ms Harris, Mr Biden selected a former rival for the nomination whose most memorable campaign moment came during a televised debate when she criticised his past position on using bussing to integrate schools.

But Ms Harris was regarded as a relatively safe choice. She is a more dynamic campaigner than Mr Biden and will be relied upon to help energise black voters, who represent a crucial constituency for Mr Biden in election battleground states.