Election 2024 updates: Michelle Obama to speak at DNC this week

Prime-time convention programming will air live from the United Center in Chicago from 6:30-11 p.m. ET on Monday and 7-11 p.m. ET on Tuesday through Thursday.

Beyond the nominee acceptance speeches --vice presidential nominee Tim Walz on Wednesday and presidential nominee Kamala Harris on Thursday -- programming has not been finalized or announced yet.

It has been confirmed, however, that "current and past Presidents are expected to participate in convention programming." President Joe Biden, Former President Barack Obama and Bill and Hillary Clinton are all tentatively slated to speak at the convention, sources familiar have told ABC News.

Much of the rest of the schedule will be rolled out in the coming days.

High-profile political leaders are also expected to make remarks at the DNC's Constituency Caucuses and Councils meetings that will take place throughout the week. Celebrities are also expected throughout the week, with a number of big names announced already to participate in events adjacent to the convention, including John Legend, Jon Stewart, Billy Porter, Joan Jett, Octavia Spencer, DJ D-Nice and Lil Jon.

-ABC News' Isabella Murray and Brittany Shepherd

Robert F. Kennedy Jr. plans to appear in Pennsylvania and New York courts next week to defend himself in lawsuits, brought by Democrat-aligned groups, that challenge the validity of voter signatures he was required to gather to make the ballot as an independent candidate.

"Mr. Kennedy will now be testifying in court next week in Harrisburg, PA, on Tuesday and Mineola, NY, on Wednesday or Thursday to defend ballot access challenges," campaign spokeswoman Stefanie Spear told ABC News in a statement.

Spear added that RFK Jr.'s campaign has canceled its event in Chicago on Sunday and Monday next week in preparation of the court appearances.

The Pennsylvania case mirrors one that Kennedy lost this month in upstate New York, as it argues he listed on his nominating petition forms an address where he doesn’t live.

Plaintiffs in the Long Island case argue that contractors hired by the Kennedy campaign to gather signatures engaged in fraudulent activity, citing a New York Times piece in May that quoted voters who said Kennedy-aligned petitioners who approached them folded over the page to conceal Kennedy's name.

"We should make it very clear that nobody wanted this to happen and did everything they could to make it stop happening," William F. Savino, a lawyer representing Kennedy in the case, told ABC News Thursday.

"Nobody wanted improper signatures, and we had the luxury of so many extra signatures, there was no incentive to bend the rules or fold the paper," Savino added.

-ABC News' Will McDuffie

President Biden was joined by a notable guest at the White House earlier Thursday: fictional former President Jed Bartlet, or actor Martin Sheen from "The West Wing."

Sheen did not travel with the president, but stepped out with him to watch Marine One depart. Sheen was joined by Melissa Fitzgerland and Mary McCormack, fellow "West Wing" cast members who are releasing a book about the show.

-ABC News' Justin Gomez

The Trump campaign has made a series of familiar new hires with a little more than 80 days left until the election.

Trump announced Corey Lewandowski, his former 2016 campaign manager, is joining his 2024 campaign as a senior adviser, while making clear that his campaign is still being spearheaded by Chris LaCivita and Susie Wiles.

"The Enthusiasm is GREAT, and the Management Team, headed up by Susie Wiles and Chris LaCivita, is THE BEST. Many people want to join the Campaign for the final push, some from the first two Campaigns -- And we want as many as we can get," Trump posted on his social media platform.

It comes as earlier this week, ABC News confirmed Taylor Budowich, who had been leading pro-Trump super PAC MAGA Inc., left the super PAC to join the Trump campaign as a senior adviser.

Alex Bruesewitz, who has been an active conservative voice online, also joined the campaign recently, ABC News confirmed. More staff hires are expected to be announced.

-ABC News' Soorin Kim, Lalee Ibssa and Kelsey Walsh