Senator Kamala Harris of California is interviewed after the second night of the first Democratic primary debate in Miami, Florida, the United States, on June 27, 2019. Photo: Xinhua

US Senator Kamala Harris accepted the Democratic nomination for vice president on Wednesday, imploring Americans to elect Joe Biden in November and accusing President Donald Trump of failed leadership that had cost lives and livelihoods during a pandemic.

Making history as the first Black woman and Asian-American on a major US presidential ticket, Harris said Trump's divisive leadership had brought the country to an "inflection point" and made a direct appeal to the party's diverse electorate whose vote is crucial to defeat Trump on November 3.

"The constant chaos leaves us adrift, the incompetence makes us feel afraid, the callousness makes us feel alone. It's a lot," the California senator and former prosecutor, speaking from an events center in Biden's hometown of Wilmington, Delaware, that was largely empty because of the coronavirus outbreak.

"We must elect a president... who will bring all of us together - Black, White, Latino, Asian, Indigenous - to achieve the future we collectively want. We must elect Joe Biden," she said in a statement.

Former US president Barack Obama, speaking just before Harris, also delivered a sharp rebuke of his Republican successor, saying Trump had used the power of his office only to "help himself and his friends."

Obama, whose vice president was Biden from 2009-2017, said he had hoped that Trump would take the job seriously, come to feel the weight of the office, and discover a reverence for American democracy.

"For close to four years now he has shown no interest in putting in the work... no interest in treating the presidency as anything but one more reality show that he can use to get the attention he craves," Obama said, in unusually sharp criticism of a sitting president by a former president.

Harris' nomination capped the third night of a party convention that has featured a crush of women headliners, moderators and speakers, showcasing the growing power of women in politics and in the Democratic Party. Biden leads Trump in opinion polls, bolstered by a big lead among women voters.

Biden, 77, would be the oldest person to become president if he is elected, leading to speculation he will serve only one term.

Reuters