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.
The second night of the DNC is officially underway in Chicago.
Tonight's theme is "A bold vision for America's future" and will feature a keynote address by former President Barack Obama.
The convention will also hold a ceremonial roll call for Harris, who became the official Democratic presidential nominee following a virtual roll call earlier this month.
A group of Israeli and American artists showcased their work throughout the day Tuesday to draw attention to the more than 100 hostages still being held by Hamas in Gaza.
The Israeli American Council (IAC), a nonprofit organization that advocates for the Israeli American community, held the pop-up exhibition it called "Hostage Square" in an empty lot about five blocks east of the United Center, where the DNC is being held through Thursday.
All the art was created in response to the Oct. 7 attacks in Israel, said Jeff Aeder, a Chicago-based real estate investor who put the exhibition together over the last four weeks.
The show "is a much more effective way at looking at a different narrative, opposed to two groups yelling at each other, to highlight the plight of the hostages and the trauma that has been felt by the Jewish world," he said. "Art is a good way for people to tell these stories."
Throughout the day Tuesday, about a thousand people visited the exhibition, according to Aeder, including Michael Herzog, Israeli ambassador to the U.S., and families of several hostages.
Aeder said he is determining if the art will travel to different locations. He said he is realistic, knowing "it's very hard" to summon change through artwork. But he hopes the exhibition is one of "a thousand different points of contact" with the public to create awareness about the plight of the hostages and their families.
"We need to continually do everything we can to bring attention to it, because we never know what’s going to touch somebody," he said. "Being silent is not an option."
-ABC News' Mark Guarino
Sanders is slated to speak in the 9 p.m. ET hour tonight, and according to released excerpts of his speech, he will focus on the economy.
The independent senator worked with the Biden-Harris administration to achieve price negotiations with Medicare on commonly used prescription drugs. The administration announced last week that a deal was reached to lower the cost of 10 medications.
"When the political will is there, government can effectively deliver for the people of our country," Sanders will say. "We need to summon that will again -- because too many of our fellow Americans are struggling every day to just get by -- to put food on the table, pay the rent, and get the health care they need."
"These oligarchs tell us we shouldn’t tax the rich; we shouldn’t take on price gouging; we shouldn’t expand Medicare to cover dental, hearing and vision; and we shouldn’t increase Social Security benefits for struggling seniors," he'll go on to say. "Well I’ve got some bad news for them. That is precisely what we are going to do, and we're going to win this struggle because this is precisely what the American people want from their government."
-ABC News' MaryAlice Parks
Before the Obamas take the stage Tuesday, the DNC will feature speeches from second gentlemen Doug Emhoff, Senate Majority Leader Chuck Schumer and Sen. Bernie Sanders, according to the convention's schedule.
Maryland Senate candidate Angela Alsobrooks will deliver the keynote remarks.
Remarks are also expected from former Trump White House press secretary Stephanie Grisham, as well as Jason Carter and Jack Schlossberg, the grandsons of former Presidents Jimmy Carter and John F. Kennedy, respectively.
