DNC Day 3: Barack Obama, Hillary Clinton urge Americans to vote as Kamala Harris accepts VP nomination

WILMINGTON, Del. (AP) - Former President Barack Obama warned Wednesday night that American democracy may not survive if Donald Trump is reelected, delivering a scathingly remarkable assessment of his successor at the Democratic National Convention. Then delegates broke a historic barrier by nominating Kamala Harris as Joe Biden's running mate and the first Black woman on a national political ticket.

Obama, himself a barrier breaker as the nation's first Black president, pleaded with voters to “embrace your own responsibility as citizens – to make sure that the basic tenets of our democracy endure. Because that’s what is at stake right now. Our democracy.”

RELATED: Kamala Harris, in historic VP nomination acceptance speech, says America at 'inflection point'

The third night of the Democrats’ four-day convention stood out for its urgent focus on voting and the party’s commitment to progressive values on issues like gun violence and climate change. Democrats targeted Trump’s policies as dangerous, casting him as cruel in his treatment of immigrants, disinterested in the nation’s climate crisis and over his head on virtually all of the nation’s most pressing challenges.

At the same time, high-profile party figures spoke directly to women and all voters of color, whose energy this fall could ultimately decide the outcome.

Harris, a 55-year-old California senator and daughter of Jamaican and Indian immigrants, addressed race and equality in a personal way Biden cannot when he formally accepts his party's presidential nomination on Thursday.

“There is no vaccine for racism. We have got to do the work,” Harris said, her words emphatic though she was speaking in a largely empty arena near Biden’s Delaware home.

“We’ve got to do the work to fulfill the promise of equal justice under law,” she added. “None of us are free until all of us our free.”

Just 76 days before the election, Biden faces the difficult task of energizing each of the disparate factions that make up the modern-day Democratic Party – a coalition that spans generation, race and ideology. And this fall voters must deal with concerns over the COVID-19 pandemic that has created health risks for those who want to vote in person.

Biden leads many polls, but his supporters report being motivated far more by antipathy toward Trump than genuine excitement about Biden, a 77-year-old white man who has spent nearly a half century in politics.

Democrats hope that Harris and Obama in particular can help bridge the divide between those reassured by Biden’s establishment credentials and those craving bolder change.

The pandemic has forced Biden's team to abandon the traditional convention format in favor of an all-virtual affair that has eliminated much of the pomp and circumstance that typically defines political conventions.

And after two nights that featured several Republicans, Democrats on Wednesday emphasized their party’s values on issues like climate change and gun violence, issues that particularly resonate with younger voters.

On guns, Biden wants to repeal a law shielding firearm manufacturers from liability lawsuits, impose universal background checks for purchases and ban the manufacture and sale of assault weapons and high capacity magazines. On climate, Biden has proposed a $2 trillion plan to invest in clean energy and end carbon emissions from U.S. power plants by 2035, even though his proposals don’t go as far as activists' preferred “Green New Deal.”

RELATED: Barack Obama, in scathing rebuke of Trump at DNC, warns democracy at stake in 2020 election

A face of the Democrats' support for gun control, former Arizona Rep. Gabby Giffords reflected on her own journey of pain and recovery from a severe brain injury nearly a decade after being shot in the head while meeting with constituents. She urged America to support Biden.

“I struggle to speak, but I have not lost my voice,” Giffords said. “Vote, vote, vote.”

Next week it's Trump's turn.

The president, who abandoned plans to host his convention in North Carolina and Florida, is expected to break tradition and accept his nomination from the White House lawn.

Trump spent much of this week hosting campaign events in battleground states in an attempt to distract from the Democrats' virtual festivities. While he did not travel on Wednesday, the Republican president railed against Biden and his party at a press conference while praising a conspiracy theory group that claims Trump's opponents have links to satanism and child sex trafficking.

“We’re saving the world from a radical left philosophy that will destroy this country,” Trump said. "And when this country is gone, the rest of the world would follow.”

Hyperbole and praise for far-right extremists has become a hallmark of Trump’s presidency, which has inflamed tensions at home and alienated allies around the world.

Voting was a dominant theme for Democrats on Wednesday.

Harris insisted that Democrats to have a specific “voting plan” to overcome the obstacles raised by the coronavirus pandemic and postal slowdowns.

She warned that the nation is at a critical point,struggling under Trump’s “chaos,” “incompetence”and “callousness.”

“We can do better and deserve so much more,” Harris said. “We must elect a president who will bring something different, something better, and do the important work. A president who will bring all of us together — Black, White, Latino, Asian, Indigenous — to achieve the future we collectively want.”

Hillary Clinton, the first woman nominated for president by a major party, spoke, too.

“For four years, people have said to me, ‘I didn’t realize how dangerous he was.’ ‘I wish I could go back and do it over.’ Or worst, ‘I should have voted,’” Clinton said. “Well, this can’t be another woulda coulda shoulda election.”

She added: “Vote like our lives and livelihoods are on the line, because they are.”

Obama hopes to serve as a bridge between those reassured by Biden’s lengthy resume and more moderate record, and a younger generation of Democrats agitating for more dramatic change.

“Donald Trump hasn’t grown into the job because he can’t,” Obama charged, speaking from the Museum of the American Revolution in Philadelphia, a backdrop chosen to reinforce what the former president sees as the dire stakes of the moment.

“I have sat in the Oval Office with both of the men who are running for president,” Obama continued, describing Biden as his brother. “I never expected that my successor would embrace my vision or continue my policies. I did hope, for the sake of our country, that Donald Trump might show some interest in taking the job seriously.”

Obama confidants say that the former president’s support for Biden is unequivocal, but he does worry about enthusiasm among younger voters, particularly younger voters of color. Democrats concede that one of the reasons Trump won the presidency in 2016 was because those voters didn't show up in the same large numbers as when Obama was on the ballot.

RELATED: WHAT TO WATCH: Joe Biden's agenda and reviving Obama era enthusiasm

Beyond the carefully scripted confines of the virtual convention, there were modest signs of tension between the moderate and progressive wings of Biden’s Democratic Party.

In particular, some progressives complained that pro-Biden Republicans such as Ohio Gov. John Kasich have been featured more prominently than the party’s younger progressive stars like New York Rep. Alexandria Ocasio-Cortez.

Climate activists also complained that the party appeared ready to drop a provision in the platform that calls for an end to fossil fuel industry subsidies and tax breaks.

Sen. Elizabeth Warren, a favorite of progressives for demanding bold change, only spoke for around five minutes.

It remains to be seen whether the unconventional convention will give Biden the momentum he’s looking for.

Preliminary estimates show that television viewership for the first night of the virtual convention was down compared with the opening of Hillary Clinton’s onsite nominating party four years ago.