Former Vice President Joe Biden is done being gracious. Sen. Cory Booker is banking on being himself. Andrew Yang wants to stay above the fray.

The 20 Democrats vying for the presidency prepped for their second bout by fine-tuning their messaging, sharpening their attacks and retooling their policy proposals. This week's Democratic debate — hosted by CNN — is being held at the Fox Theatre in Detroit over two nights, July 30 and 31. Ten candidates will be on the stage each night. CNN's Dana Bash, Don Lemon and Jake Tapper are moderating.

Here's how some of the 10 candidates taking the stage on Wednesday night have prepped:

Joe Biden: "Not going to be as polite"

The front-runner in the polls has fielded a litany of attacks from his fellow Democrats since the first debate, particularly from Sen. Kamala Harris of California, whose stand-out confrontation with the vice president boosted her campaign.

This time around, Biden — as he put it last week — is “not going to be as polite.” The seasoned statesman is preparing to directly spar with Harris again, as well as other contenders hoping to blast him to improve their standing among voters. Ahead of the debate, Biden has attacked "Medicare for All" proposals and worked to maintain his support among black voters.

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His campaign also said not to expect any fireworks between him and Warren, who is ideologically similar to Sanders and also surging in polls.

Cory Booker: Be yourself

Booker, who has remained relatively stagnant in the polls, plans to be himself when he hits the stage for Night Two of the debate, the New Jersey senator's campaign aides said.

“Honestly, people are still getting to know Cory Booker … be yourself is our best advice to him and when he does that, people like him and end up voting for him,” Addisu Demissie, Booker’s campaign manager, said.

Booker's campaign said his strategy will be twofold — arguing that he’s the right candidate to take on Trump and making the case that he has a record of getting progressive policies passed. Booker’s campaign also said that he will not be scared to attack Biden directly on the debate stage after having criticized the former vice president on the campaign trail.

“He’s not somebody who’s afraid to speak truth to power when it demands it,” Demissie said.

Julian Castro: Maintaining the momentum

The former Housing and Urban Development secretary had a standout moment at the first debate when he sparred with former Texas congressman Beto O’Rourke over immigration. For the second debate — appearing on the second night — Castro is prepping with the same campaign team, staging mock debates, practicing getting his policy points under one minute, and focusing on issues that “every American family cares about.”

“I want to make sure I speak to them about health care, education, job opportunities,” Castro said, “making sure that America leads around the world again.”

His campaign plans to focus on drawing distinctions between Castro’s policies and those of the other candidates, as well as Trump.

Kirsten Gillibrand: Elbows out

This second debate could be a make or break moment for the New York senator's campaign. In the first debate, Gillibrand’s campaign staff had prepped her to insert herself in order to get more speaking time, but she only ending up speaking roughly seven minutes.

For this second debate, her campaign is prepping her to fight for her values, an adviser to the campaign said.

Gillibrand is in Troy, New York, having multiple debate sessions ahead of her appearance on Night One of the debate. These sessions have included podiums and one or two staffers taking the role of other candidates, delivering quotes and ideas of her rivals.

Bill de Blasio: Likable enough?

In the first debate, the New York City mayor showed off his sharp elbows as he interrupted his foes to give a staunch defense of progressive values and take direct shots at President Donald Trump. This time around, his campaign said that de Blasio — who has had high unfavorability among Democrats in some polls — will adjust his performance.

“There are legitimate contrasts between the candidates and their positions in this battle for the heart and soul of the Democratic Party,” Jaclyn Rothenberg, de Blasio’s press secretary, said in a statement to NBC News.

De Blasio, Rothenberg said, is doing test-runs of his opening and closing remarks, running drills and honing responses to specific candidates. His debate snacks of choice include chips and guacamole, mixed nuts and water.

Andrew Yang: Stay above the fray

Andrew Yang loves to study, especially now that he knows the format this time around. The entrepreneur has been holding full mock debates, drills and video reviews, a senior campaign official said.

The key to Yang’s strategy? Staying above the infighting.

A senior campaign official said Yang "can calmly stay above the canned attack lines and reality TV show actions, and lay out our vision to the American people." The official is hoping Yang will have more time in the fall debate should he qualify to explain his stances on the issues.

Jay Inslee: Practicing and biking

Washington Gov. Jay Inslee is preparing for his debate appearance on Wednesday by memorizing his opening and closing statements, practicing debate techniques with his staff and going for a bike ride on the Detroit waterfront.

CORRECTION (July 30, 2019, 3:10 p.m. ET): A previous version of this article misspelled the last name of the governor of Washington. He is Jay Inslee, not Insee.