Obama praised President Biden and offered support for Harris.
Vice President Kamala Harris officially became the official Democratic presidential nominee during the second night of the Democratic National Convention.
The night included a lively and upbeat roll call vote of delegates that featured a DJ, some celebrities and energetic speeches. Also, Harris, who campaigned in Milwaukee, thanked the crowd in a live-streamed message.
Second gentleman Doug Emoff talked about his long relationship with Harris and touted her vision for the country.
But the night's biggest headline was the return of former President Barack Obama and first lady Michelle Obama to the DNC stage. Both stressed what's at stake in this election and pushed Americans to come together to bring the country to a better future.
Emhoff sent the crowd into a tizzy after attendees had been lagging in energy.
The first gentleman told a story of his first date with Harris, prompting cheers when describing by an awkward voicemail he sent her.
-ABC News' Tal Axelrod
Michelle Obama reflected on her mother's memory and the values that she instilled in her from an early age.
"Kamala Harris and I built our lives on those same foundational values. Even though our mothers grew up an ocean apart, they shared the same belief in the promise of this country," she said.
Obama continued to tout Harris' skills, experience and temperament during her years of service.
"Kamala Harris is more than ready for this moment," she said. "She is one of the most qualified people ever to seek the office of the presidency."
The crowd at the United Center greeted former first lady Michelle Obama with a standing ovation as she took the stage as the penultimate speaker.
Michelle Obama said until recently she had mourned the "dimming" of hope felt in the country following the recent developments in the country and the loss of her mother.
However, she said she recently felt it spreading again.
"America, hope is making a comeback," she said.
Second gentleman Doug Emhoff re-introduced himself to America in a personal, down-to-earth speech as Harris makes a historic bid for the White House that, if elected, would make him the first-ever first gentleman.
He said he grew up the son of two Brooklynites and had a "typical suburban childhood."
"The guys I grew up with are still my best friends. The group chat is active every day -- and it's probably blowing up right now," he said.
He said he worked at McDonald's in high school when money was tight and worked full-time so he could afford to go to college part-time.
"Thanks to partial scholarships, student loans and a little help from my dad, I got myself through law school and got my first job as a lawyer -- which is also where I met the guys in my fantasy football league," he said. "A lot has changed in our lives since the early '90s, but my team name is still Nirvana -- yes, after the band."
He said he loved working as a lawyer, became a dad to Cole and Ella, got a divorce and then "something unexpected happened" -- he was set up on a blind date with Harris. He said Harris saved his first bumbling voicemail to her "and she makes me listen to it on every anniversary."
On Harris, he said she "finds joy in pursuing justice."
"She stands up to bullies -- just like my parents taught me to. She likes to see people do well -- and hates when they're treated unfairly. She believes this work requires a basic curiosity in how people are doing. Her empathy is her strength."
He talked about Harris coming to synagogue with him and making a "mean brisket for Passover." He said Harris encouraged him as second gentleman to fight against antisemitism.
On their blended family, he said that Harris has "always been there for our children, and I know she'll always be there for yours too."
"Kamala is a joyful warrior," he said. "It's doing for her country what she has always done for the people she loves. Her passion will benefit all of us when she's our president."
This Thursday, as Harris accepts the party's nomination for president, will be their 10th wedding anniversary, he noted.
"Kamala was exactly the right person for me at an important moment in my life. And at this moment in our nation's history, she is exactly the right president," he said.
Doug Emhoff on wife Kamala: ‘She’s ready to lead’
