DNC Day 1: President Biden says 'America is winning' and Trump is a 'loser'

United Auto Workers President Shawn Fain took the stage and began by thanking President Joe Biden for joining the picket lines during their strikes against the major auto companies last year.

Fain praised Vice President Kamala Harris for her years of supporting the UAW and for fighting for workers' rights.

"It's real simple. Kamala Harris is one of us. She's a fighter for the working class. And Donald Trump is a scab," Fain said to the crowd who chanted "Trump is a scab."

Fain revealed a shirt with that statement along with "Vote Harris" midway through his speech citing Nelly's 2002 song "Hot in Here."

"It's hot in here because you're fired up and you're fed up and the American working class is fired up and fed up," he said.

United Auto Workers President Shawn Fain took the stage and began by thanking President Joe Biden for joining the picket lines during their strikes against the major auto companies last year.

Fain also called out Trump's rhetoric blaming economic problems on several groups including immigrants and LGTBQ groups.

"Trump is pushing divide and conquer tactics of the rich. It's the oldest trick in the book," he said.

"They do that because they want working-class people to be divided into focus and keep the focus off the one true enemy: corporate greed. The rich think we're stupid, but working class Americans see this for what it is," Fain added.

Golden State Warriors coach Steve Kerr got a standing ovation when he walked on stage, just over a week after he coached the U.S. Olympic men's basketball team won gold.

Chants of "USA" stretched across the convention floor as he started speaking.

Golden State Warriors coach Steve Kerr got a standing ovation when he walked on stage, just over a week after he coached the U.S. Olympic men's basketball team won gold.

"It was the proudest moment of my life," he said, recounting the team's victory in Paris earlier this month.

Kerr called the audience to action -- asking the country to follow in the footsteps of the American basketball team's gold medal performance in Paris.

"After the results are tallied [on election] night, we can, in the words of the great Steph Curry, we can tell Donald Trump, 'night-night.'"

Convention staff is preparing for possible disruptions over Gaza during President Joe Biden's keynote speech.

ABC News has heard from staff and activists that they likely won't come from uncommitted delegates on the convention floor, but are expected to come from activists who have passes into the arena who are in sections higher up.

Harris sent the crowd into a frenzy when she walked onto the stage at the United Center, with attendees jumping to their feet in surprise.

"It is so good to be with everyone this evening in this hall and everyone at home. This is going to be a great week," she said to more applause.

Harris also gave Biden his flowers, sparking chants of "USA!"

Harris sent the crowd into a frenzy when she walked onto the stage at the United Center, with attendees jumping to their feet in surprise.

"And I want to kick us off by celebrating our incredible president, Joe Biden, who will be speaking later tonight," she said. "We are forever grateful to you."

Harris walked off to her campaign anthem, Beyonce's hit song "Freedom."