'Important moment': Biden to speak at Democratic National Convention, White House says

President Joe Biden will speak at the Democratic National Convention next week in Chicago, the White House said on Monday.

"He's looking forward to, as he tends to do, speak directly to the American people," White House press secretary Karine Jean-Pierre said, "talk about the moment that we're at, what's at stake, and continue to talk about an issue that is incredibly important to him, which is unity, making sure that we're unified and we continue to do the work that the president has been successful in doing in the past three and a half years."

Jean-Pierre said Biden will spend time over the next few days focusing on his upcoming remarks.

"I think you can expect this president to take this moment," she said. "He understands this is an incredibly important moment ... He's still very much the leader of the party, right? And he takes that very seriously. And he's also very proud of his vice president."

Sources had told ABC News that Biden, former President Barack Obama, former President Bill Clinton and former Secretary of State Hillary Clinton are all tentatively slated to speak at the DNC.

The convention will take place from Aug. 19 through Aug. 22. Vice President Kamala Harris, who quickly rallied the party to her side after Biden dropped out of the 2024 race and endorsed her, was officially certified as the Democratic Party's nominee last week.

Sources said the working speaking schedule, which can change, has Biden giving a speech on Monday night, as well as Hillary Clinton; Obama speaking on Tuesday, vice presidential nominee Gov. Tim Walz and Bill Clinton speaking on Wednesday, and Harris speaking on Thursday.

Little over a month ago, it was all but certain Biden would be on stage at the DNC to accept the nomination. But after a poor debate performance against Donald Trump set off a firestorm of doubt among Democrats about Biden's age and fitness to serve a second term, Biden announced he was exiting the race on July 21.

In an interview that aired Sunday on CBS, Biden elaborated on his decision not to run for reelection.

The president first cited calls from his Democratic colleagues, including former House Speaker Nancy Pelosi, who were worried about how it might impact down-ballot races. He said he worried questions about his viability would be a "real distraction."

He also said he considered himself as a transitional figure and that beating Trump was the most important thing for him.

"Number two, when I ran the first time, I thought of myself as being a transition president," he said. "I can't even say how old I am, it's hard for me to get out of my mouth. And, but things got moving so quickly, it didn't happen. And the combination was that I thought it was a critical issue for me still, it's not a joke, maintaining this democracy."

"But I thought it was important because although it's a great honor being president, I think I have an obligation to the country to do the most important thing, and that is we must, we must, we must defeat Trump," he said.

ABC News' Alexandra Hutzler contributed to this report.