WASHINGTON — US Senator Kamala Harris accepted the Democratic nomination for vice-president on Wednesday, imploring the country 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, Ms. Harris made a direct appeal to Black Americans and other crucial constituencies that Democrats need in the Nov. 3 election.

“The constant chaos leaves us adrift, the incompetence makes us feel afraid, the callousness makes us feel alone. It’s a lot,” she said, speaking from an events center in Mr. 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,” Ms. Harris said.

On the third night of a four-night convention that has featured a crush of women headliners, moderators and speakers, Ms. Harris pressed the case against Mr. Trump, saying his divisive leadership had brought the country to an “inflection point.”

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

Mr. Obama, whose vice-president was Mr. Biden from 2009-2017, said he had hoped that Mr. 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,” Mr. Obama said, in unusually sharp criticism by a former president of a sitting president.

In a speech from the Museum of the American Revolution in Philadelphia, Mr. Obama warned Mr. Trump and Republicans were trying to make it harder for Americans to vote and called Mr. Trump’s leadership a threat to democracy.

“We can’t let that happen. Do not let them take away your power. Don’t let them take away your democracy. Make a plan right now for how you’re going to get involved and vote. Do it as early as you can and tell your family and friends how they can vote too,” Mr. Obama said.

Democrats have been alarmed by Mr. Trump’s frequent criticism of mail-in voting, and by cost-cutting changes at the US Postal Service instituted by Postmaster General Louis DeJoy, a Trump supporter, that could delay mail during the election crunch. Mr. DeJoy said recently he would delay those changes until after the election.

Former first lady and US Secretary of State Hillary Clinton, the 2016 Democratic presidential nominee who lost to Mr. Trump, told the convention she constantly hears from voters who regret backing Mr. Trump or not voting at all.

“This can’t be another woulda coulda shoulda election,” Ms. Clinton said. “No matter what, vote. Vote like our lives and livelihoods are on the line, because they are.”

Ms. Clinton, who won the popular vote against Mr. Trump but lost in the Electoral College, said Mr. Biden needs to win overwhelmingly, warning he could win the popular vote but still lose the White House.

“Joe and Kamala can win by 3 million votes and still lose,” Ms. Clinton said. “Take it from me. So we need numbers overwhelming so Trump can’t sneak or steal his way to victory.”

Mr. Biden leads Mr. Trump in opinion polls, bolstered by a big lead among women voters. Throughout the convention, Democrats have appealed directly to those women voters, highlighting Mr. Biden’s co-sponsorship of the landmark Violence Against Woman Act of 1994 and his proposals to bolster childcare and protect family healthcare provisions.

Democrats also broadcast videos highlighting Mr. Trump’s crackdown on immigration, opposition to gun restrictions and his decision to pull out of the Paris climate accord. — Reuters