WILMINGTON, Del. — For­mer Pres­i­dent Barack Oba­ma warned that Amer­i­can democ­ra­cy could fal­ter if Pres­i­dent Don­ald Trump is reelect­ed, a stun­ning rebuke of his suc­ces­sor that was echoed by Kamala Har­ris at the Demo­c­ra­t­ic Con­ven­tion as she embraced her his­toric role as the first Black woman on a nation­al polit­i­cal ticket.

Oba­ma, him­self a bar­ri­er break­er as the nation’s first Black pres­i­dent, plead­ed with vot­ers Wednes­day night 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.”

Through­out their con­ven­tion, the Democ­rats have sum­moned a col­lec­tive urgency about the dan­gers of Trump as pres­i­dent. In 2016, they dis­missed and some­times triv­i­al­ized him. Now they are cast­ing him as an exis­ten­tial threat to the coun­try. The tone sig­nals anew that the fall cam­paign between Trump and Joe Biden, already expect­ed to be among the most neg­a­tive of the past half-cen­tu­ry, will be filled with ran­cor and recrimination.

Yet on the third night of the Democ­rats’ four-day con­ven­tion, par­ty lead­ers also sought to put for­ward a cohe­sive vision of their val­ues and pol­i­cy pri­or­i­ties, high­light­ing efforts to com­bat cli­mate change and tight­en gun laws. They drew a sharp con­trast with Trump, por­tray­ing him as cru­el in his treat­ment of immi­grants, dis­in­ter­est­ed in the nation’s cli­mate cri­sis and in over his head on vir­tu­al­ly all of the nation’s most press­ing challenges.

Democ­rats also demon­strat­ed a hope that Biden, a 77-year-old white man, can revive the coali­tion that helped put Oba­ma into office, with minori­ties, younger vot­ers and col­lege-edu­cat­ed women blunt­ing Trump’s lock on many white and rur­al voters.

The evening marked a cel­e­bra­tion of the party’s lead­ing women, includ­ing remarks from Hillary Clin­ton, the first woman to become a major tick­et pres­i­den­tial nom­i­nee; House Speak­er Nan­cy Pelosi and Mass­a­chu­setts Sen. Eliz­a­beth War­ren, who chal­lenged Biden dur­ing the pri­ma­ry and is now sup­port­ing his campaign.

Har­ris, a 55-year-old Cal­i­for­nia sen­a­tor and the 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 are free.”

Just 75 days before the elec­tion, Biden must ener­gize the dis­parate fac­tions that make up the mod­ern 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 — and postal slow­downs for mail-in bal­lots, which Democ­rats blame on Trump.

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 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. It was com­plete­ly silent, for exam­ple, as Har­ris took the stage to make his­to­ry at the Chase Cen­ter in down­town Wilm­ing­ton. She was flanked by Amer­i­can flags but no fam­i­ly, and her audi­ence con­sist­ed of a few dozen reporters and photographers.

After two nights that fea­tured sev­er­al Repub­li­cans, the pro­ceed­ings on Wednes­day empha­sized core Demo­c­ra­t­ic val­ues on areas like cli­mate change and gun vio­lence 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.

Wednes­day night, 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 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.”

It’s Trump’s turn next. The Repub­li­can pres­i­dent, who aban­doned plans to host his con­ven­tion in North Car­oli­na and in Flori­da, is expect­ed to break tra­di­tion and accept his nom­i­na­tion from the White House lawn.

In the mean­time, he’s seek­ing to take atten­tion from Biden. Trump will stop near his Demo­c­ra­t­ic rival’s birth­place of Scran­ton, Penn­syl­va­nia, on Thursday.

Late Wednes­day, Trump tweet­ed about Oba­ma and Clin­ton, taunt­ing: “Wel­come, Barack and Crooked Hillary. See you on the field of battle!”

Clin­ton implored Democ­rats in her speech to turn out in larg­er num­bers in Novem­ber to block his reelection.

“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,’” said Clin­ton, the first woman nom­i­nat­ed pres­i­dent by a major par­ty. “Well, this can’t be anoth­er woul­da coul­da shoul­da election.”

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

Oba­ma spoke harsh­ly of Trump, too.

“Don­ald Trump hasn’t grown into the job because he can’t,” Oba­ma said, 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 wor­ries 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.

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.

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

And while War­ren urged peo­ple to vote for Biden and gave a hearty endorse­ment for sev­er­al of his eco­nom­ic and child care plans, she hint­ed that she would not retreat from her push for a more pro­gres­sive agen­da should her par­ty retake the White House.

“We all need to be in the fight to get Joe and Kamala elect­ed,” War­ren said. “And after Novem­ber, we all need to stay in the fight to get big things done.”