Clinton said the the US election would be "'We The People' versus 'Me, Myself and I,'" firing up Wednesday's third night of the DNC before vice presidential nominee Tim Walz got the chance to introduce himself to a national audience.
Clinton was once declared the "secretary of explaining stuff" by Barack Obama, whose re-election bid in 2012 was bolstered by a rousing Clinton speech at that year's DNC. Now 78 - the same age as Trump - Clinton's delivery was sometimes halting but he delivered homespun lines about the November election and urged Democrats to back Harris.
"What does her opponent do with his voice? He mostly talks about himself," Clinton said. "So the next time you hear him, don't count the lies, count the I's."
Clinton also said he was glad to have "a coach on our team," warming up for Walz, the Minnesota governor who has become known among supporters as a folksy, Midwestern teacher, football coach and dad.
Walz will accept the Democratic nomination for vice-president with 11 weeks to go before he and Harris face Republican former president Trump in the election.
The pair received a ringing endorsement on Tuesday from former president Barack Obama and his wife Michelle Obama at the Chicago convention.
"I love this guy," Obama said of Walz.
"He knows who he is and what's important. You can tell those flannel shirts he wears don't come from some consultant. They come from his closet and they've been through some stuff."
Stevie Wonder told the Democratic National Convention the US "must choose courage" at the election. (AP PHOTO)
Walz's rapid rise to national fame has drawn Republican scrutiny and prompted the Harris campaign to issue statements about his 24-year military history and the method of fertility treatment he and his wife underwent to have children.
Earlier Stevie Wonder implored the DNC, "We must choose courage over complacency" before performing Higher Ground as a troupe of dancers grooved nearby.
Also speaking on Wednesday were Transportation Secretary Pete Buttigieg, former House Speaker Nancy Pelosi and House Minority Leader Hakeem Jeffries. Talk show host Oprah Winfrey was also making an appearance.
Meanwhile, Trump has spoken from behind bulletproof glass at his first outdoor rally since last month's attempted assassination.
Donald Trump speaks behind a glass barrier during a campaign rally at North Carolina. (AP PHOTO)
During an event in North Carolina focused on national security, he blamed President Joe Biden and Harris for the deadly Afghanistan withdrawal and wars in Ukraine and the Middle East, while returning repeatedly in his remarks to the Democratic gathering in Chicago.
The former president, now the Republican nominee, asked the crowd at the North Carolina Aviation Museum & Hall of Fame whether they had seen the speeches given by Obama and former first lady Michelle Obama.
"He was taking shots at your president. And so was Michelle. You know, they always say, 'Sir, please stick to policy. Don't get personal'. And yet they're getting personal all night long, these people," he said, asking: "Do I still have to stick to policy?"
Agencies