Juana Summers

On a recent Saturday night, tens of thousands of people joined a nine-hour virtual dance party on Instagram Live that was hosted by DJ D-Nice. Some familiar big names have been dropping into what he calls "Club Quarantine," like John Legend, Joe Biden and Mark Zuckerberg.

But it was the appearance of former first lady Michelle Obama that seemed to have a big impact.

"Oh my gosh. Michelle Obama's in here," D-Nice exclaimed as Obama's appearance brought the music to a brief stop. "Yo, I swear, I don't even know who to play right now. My mind's completely blown."

Updated at 12:02 p.m. ET

Former President Barack Obama officially endorsed his former vice president, Joe Biden, on Tuesday, marking the Democratic establishment's formal consolidation around the party's presumptive presidential nominee.

When Amol Jethwani interviewed for a job on Mike Bloomberg's presidential campaign in December, the benefits were unlike anything he had heard of for political campaign field workers.

"They offered an incredible benefits package, which is unheard of for field staff, offering $8,000 a month for a regional role in addition to health care, technology, laptops, cellphones," said Jethwani.

Former campaign workers for Mike Bloomberg's presidential campaign have filed two separate proposed class-action lawsuits, alleging that the thousands of staffers laid off this month had been promised to be paid through the general election in November.

One lawsuit, filed by Donna Wood, a former field organizer for Bloomberg's campaign in Florida, alleges that the campaign misled employees, recruiting them to work for Bloomberg under false pretenses and had failed to pay the necessary overtime. The lawsuit was filed in federal court in New York City.

Brianna Wu is hoping for an upset.

The software engineer is looking to challenge incumbent Rep. Stephen Lynch (D-Mass.) for a second time. But, before that, she has to get on the ballot for September's primary.

For congressional candidates like Wu, that means collecting 2,000 signatures, no large number. But with in-person contact several limited by the coronavirus outbreak, even that feels impossible now.

The revolution that Bernie Sanders is promising depends on a new wave of young voters showing up at the polls to propel his campaign. But this week, the Vermont senator acknowledged that those voters, on which his success to some degree hinges, have not shown up in the way he'd hoped.

After 14 states held primary contests on Super Tuesday, Sanders acknowledged to reporters that he'd been "disappointed" with the results.

Former Vice President Joe Biden went on a romp across the South on Tuesday, winning over several states with large majorities of African Americans. Vermont Sen. Bernie Sanders won the largest state on the Super Tuesday map, California, where Latinos make up about a third of the Democratic electorate.

All told, the 14 states that voted Tuesday offer the clearest distillation yet of the two distinct paths that Sanders and Biden would take to build a winning Democratic coalition to defeat President Trump in November.

Updated at 9:36 p.m. ET

Tom Steyer, the billionaire hedge fund investor and environmental activist who staked his campaign on a strong finish in South Carolina, suspended his presidential campaign on Saturday.

Steyer aggressively courted the black vote in the state, with a focus on racial and economic justice but had a disappointing finish. Former Vice President Joe Biden was projected to win the state.

Democratic presidential hopefuls have stepped up their criticism of President Trump's handling of the coronavirus, accusing his administration of "incompetence."

The president has noticed. Speaking to supporters Friday night in South Carolina, he accused his Democratic rivals of using the virus for political ends.

As Tuesday's Democratic presidential primary debate came to a close, each of the candidates was asked to name the biggest misconception voters have about them.

A day later, the question was still on the mind of Tom Steyer, the billionaire hedge fund investor who has barnstormed South Carolina, aggressively courting the black vote with a focus on racial justice and climate issues.

Former New York City Mayor Michael Bloomberg has now spent some $452 million on advertising since entering the Democratic presidential race in late November, according to the ad-tracking firm Advertising Analytics.

The multibillionaire, who is self-funding his campaign, has already spent more than $401 million on television and radio ads alone. That surpasses the $338.3 million that President Barack Obama's campaign spent on those ads during his entire 2012 campaign, according to Advertising Analytics.

Former Vice President Joe Biden has suffered back-to-back poor showings in the first two states to vote in the Democratic primary, and there are now serious questions about whether his "electability" argument is still plausible.

The Democratic National Committee announced new rules for getting on stage for the party's Feb. 19 debate in Nevada — and they have the potential to shake up who is on the stage.

The new qualification standards scrap the grassroots funding support threshold that candidates have had to meet for prior debates. That means former New York Mayor Michael Bloomberg, a billionaire who is self-funding his campaign and is not soliciting donations, could make his first appearance on stage.

Marlu Abarca has lived in Iowa for a decade and says she now "identifies as an Iowan." For the past few weeks, she has been attending training sessions to chair a satellite caucus site at the South Suburban YMCA in Des Moines.

She'll have to miss work to participate.

"I have to take vacation to chair the satellite caucus," Abarca, 28, said during a lunch break from her job at a Des Moines library.

During the final presidential debate of 2019, one of the moderators posed a question about a topic that rarely gets attention on the debate stage: What steps would candidates take to help disabled people get more integrated into the workforce and their local communities?

For Andrew Yang, the question was both political and personal. His oldest son, Christopher, is on the autism spectrum.

Julián Castro went to Des Moines this week and told Iowans they shouldn't vote first.

"I'm gonna tell the truth. It's time for the Democratic Party to change how we do our presidential nominating process," Castro said at a town hall dedicated to his belief that the party should shake up who has the first say of who should be president. Iowa holds its caucuses in less than two months.

Updated at 5:35 p.m. ET

Amid a labor dispute at the site of next week's presidential primary debate, all seven Democratic candidates who made the stage are siding with unions and threatening not to participate in the event.

Candidates are scheduled to meet for the Democratic presidential debate on the Loyola Marymount University campus in Los Angeles on Dec. 19.

After weeks of scrutiny over his work at consulting firm McKinsey & Company, Democratic presidential candidate Pete Buttigieg released a list of nine clients that he worked for while employed there.

When Barack Obama stood in Chicago's Grant Park facing throngs of people in 2008 and declared that "change has come to America," Arielle Monroe was a freshman in college.

Obama was her generation's rock star, who swept away the nation's last remaining racial barrier in politics and inspired a multiracial, multigenerational coalition to support him.

Updated at 12:22 ET

Former New York City Mayor Michael Bloomberg is making a late entry into the presidential race, a move that could upend the Democratic nominating contest this spring.

Bloomberg said in a statement Sunday that he is running to rebuild America and defeat President Trump, whom he says "represents an existential threat to our country and our values."

Age has been a defining factor in the race for the Democratic presidential nomination, with candidates spanning four generations.

South Bend, Ind., Mayor Pete Buttigieg, age 37, is one of the youngest presidential candidates in modern American history and, if elected, would be the youngest president ever.

Buttigieg entered the race this spring focused on the idea of generational change, often telling voters that he fears what the United States will look like in the year 2054, the year that Buttigieg will be the same age as President Trump is today.

A former aide to Barack Obama said that concerns the former president raised about ideological "purity" were aimed at explaining that governing requires having conversations that include people whose values you may not share.

Speaking Tuesday at an Obama Foundation summit in Chicago, Obama said that he worries that some in the Democratic Party's left flank are too worried about ideological "purity" among their fellow Democrats.

This story is part of NPR's series Journey Home. We're going to the places presidential candidates call home and finding out what those places tell us about how they see the world.

As Martin O'Malley neared the launch of his presidential campaign, the former Baltimore mayor and Maryland governor said he wouldn't think of announcing his bid "anyplace else," even as the city exploded with riots after the death of Freddie Gray, a young black man who was fatally injured while in police custody.

The argument over genetically modified food has been dominated, in recent years, by a debate over food labels — specifically, whether those labels should reveal the presence of GMOs.

The battle, until now, has gone state by state. California refused to pass a labeling initiative, but Maine, Connecticut and Vermont have now passed laws in favor of GMO labeling.

This story is part of NPR's series Journey Home. We're going to the places that presidential candidates call home and finding out what those places tell us about how they see the world.

Greg Demetri hit the jackpot. When he picked the location for Villa Toscana, his nearly one-year-old Italian restaurant on the main stretch of businesses in Central, S.C., he had no idea that the building had once been owned by the town's most famous resident, Sen. Lindsey Graham.

This post has been updated to note that Graham has now officially gotten into the race for president.