They have to introduce themselves to the country, contrast themselves with the other candidates, make the case for why they should be the next leader of the free world and not make any embarrassing mistakes — and their campaigns estimate they'll have about 10 minutes to do so.

Here's a look at how the 10 candidates participating in the first night of the Democratic debate on Wednesday, hosted by NBC, at the Adrienne Arsht Center for the Performing Arts in downtown Miami, are prepping for their turn in the spotlight.

Elizabeth Warren

Sen. Elizabeth Warren of Massachusetts, who polls show is the front-runner among Wednesday's debaters, has another advantage as well — recent debating experience.

Warren was re-elected in November after three bruising debates against Republican state Rep. Geoff Diehl. She ended up with about 60 percent of the vote — higher than the 54 percent she garnered when she wrested the seat from incumbent Scott Brown in 2012.

While Warren comes into the debate riding a recent surge in the polls, one person close to her campaign told NBC News that the debate is still her "opening argument" for voters who might just be tuning in to the race. Another top aide pointed to Warren's campaign schedule as an example of how she's prepared — she has done 100 town halls, fielded more than 450 voter questions and parried with reporters at 72 post-event media availabilities, according to her campaign.

Warren said she still has more to do. On Friday, outside Democratic Rep. Jim Clyburn's fish fry in Columbia, South Carolina, Warren told NBC News she was focused on "learning to talk in one-minute segments," noting with a laugh, "that’s hard!"

Beto O'Rourke

Former Rep. Beto O'Rourke of Texas — who had two heated debates with Republican Sen. Ted Cruz in October in his unsuccessful challenge — has been been busy honing his strategies, including a focus on the problems of the people he's met on the campaign trail.

"During the debate, he will lift up the stories of those he's met all across the country, connect them to the many robust plans he has outlined, and share his vision for how we can bring more people into this democracy to confront the greatest set of challenges we've ever faced," said a campaign spokesman, Ian Wilhite.

O'Rourke told NBC News that he has been preparing by "listening to people," and his campaign said he has answered nearly 1,500 questions at town halls since the campaign started.

"I'm holding town hall meetings, asking folks what's on their mind, how they would meet the greatest set of challenges that we've ever faced, and then incorporating that and hopefully reflecting that in what I say on the trail and what you see me saying on the debate stage— that we are a courageous, confident and ambitious people," O'Rourke said.

Amy Klobuchar

Sen. Amy Klobuchar of Minnesota is aiming to introduce voters to her straight-from-the-heartland message. She is expected to lean into her recently announced plan for her first 100 days in office, which includes an eye-popping 130-plus policy agenda items.

Klobuchar told the Washington Examiner that "I think the best debate prep right now is just getting out there with people, and getting the hard questions, and answering them."

Cory Booker

Sen. Cory Booker of New Jersey is pumped up for the debate — mentally and physically.

He's been prepping for the debate in sessions led by senior adviser Matt Klapper, who also was Booker's Senate chief of staff before he transitioned to the campaign. Campaign manager Addisu Demissie and a host of other staffers have also been involved in the intense preparation, which Booker has kept light by taking breaks to do pushups "to keep him motivated," a campaign aide said. He's also done bicep curls in his shirt and tie.

To maximize his time, Booker is going to focus less on attacking his rivals and policy specifics and more on what motivates him and what he cares about, his campaign said, estimating he will only have seven to 10 minutes to speak.

Julián Castro

Former Housing and Urban Development Secretary Julián Castro's campaign had yet to do any mock debates as of Monday, but was considering doing so before Wednesday night, campaign spokesman Sawyer Hackett said.

"We know a lot of the questions are going to be about pinning down the candidates on where their policies differentiate them from other candidates," Hackett said.

The campaign is working on how to get Castro’s policies, generally 10 to 15 pages each, across to the audience in limited time.

"The most important thing for this debate is making sure broadly he can talk about his experience," Hackett said. "These are a lot of voters who have not heard from him before."

Bill de Blasio

New York City Mayor Bill de Blasio had contentious three-way debates as he was running for re-election in 2017, but he also has experience with larger debates. In his first campaign for mayor in 2013, the then-long shot shared the debate stage with six Democratic rivals and stood on the — as he will be doing on Wednesday.
"I've done a lot of debates over the years and it's something I enjoy doing, and I feel like it's a great opportunity to get your message out," de Blasio told NY1.

Campaign rep Olivia Lapeyrolerie said de Blasio has been getting ready with a "mix of mock debate as well as question drills."

Jay Inslee

Washington Gov. Jay Inslee told CBS News he wants to focus on his signature issue, combatting climate change, but acknowledged it's "challenging" to condense his 200-page plan into one-minute soundbites. Inslee told NBC News on Monday that he still wants an entire debate focused on climate.

"We are going to continue this effort, but we are not waiting," he said. "We are going to start Wednesday night."

Inslee's communications adviser, Jared Leopold, acknowledged the debate will give the governor "the biggest stage we've had yet."

"We've been doing prep for a while now," he said. "It's a different ball of wax than anything we’ve ever experienced."

Tim Ryan

Rep. Tim Ryan of Ohio has been preparing by hitting the books, watching previous debates and talking to people on the campaign trail.

"He's reviewing a lot of his past work and relevant stats and data," said his communications director, Michael Zetts. "He's going to review a lot of his past bills and legislative achievements."

Ryan was doing debate prep Monday night at his brother-in-law’s house in Fort Myers, Florida, with staff tossing policy questions at him in different ways and trying to get him used to giving short answers, a campaign source told NBC News.

The congressman has been reviewing his previous performances from debates for his Ohio seat, while his staff has been watching video of some of the 2016 Republican presidential primary debates, which also offered a large field of candidates.

"We've reviewed some of the 2016 debates to see how NBC and other outlets dealt with a such a big field, to get a sense of it," Zetts said.

John Delaney

Former Maryland Rep. John Delaney's campaign has been going to the 2016 videotape as well.

"It was such a big field that it's the one that's most comparable," said Delaney's press secretary, Michael Starr Hopkins.

Hopkins said Delaney has been preparing with "a little of everything — watching a lot of video of old debates, spending a lot of time with his briefing book, going over a lot of the issues and the other candidates' policies, or lack thereof."

"We've made sure every day for the last couple of weeks that we've had time set for debate preparation," Hopkins said. "You have to be prepared for whatever comes your way. Anything can happen."

Tulsi Gabbard

Rep. Tulsi Gabbard's campaign did not respond to a request for information on how she is preparing for the debate. Gabbard resigned her post as a Democratic National Committee vice chair in 2016 after the group refused to add more debates between Sen. Bernie Sanders and Hillary Clinton, but she refused to debate her own primary opponent when she was running for re-election in Hawaii last year.