undefined undefined/iStock(DETROIT) — After Sens. Bernie Sanders and Elizabeth Warren fended off repeated attacks from moderate competitors, the next 10 presidential primary contenders take the stage Wednesday for the second night of the second Democratic debates.

During the first night, polling front-runner and former Vice President Joe Biden’s name was not mentioned once, but now he’ll share the stage with Sen. Kamala Harris, D-Calif., flanked by the all the candidates of color running in the presidential primary, after a random live drawing split the 20 qualifying contenders between the two nights.

Airing on CNN at 8 p.m. ET, Wednesday night’s debate is expected to be more contentious than Tuesday’s, picking up where the first debates in Miami left off: When Biden was relegated to playing defense after a game-changing moment for Harris and other lesser-known candidates saw spikes in fundraising and polling following much-needed breakout performances.

For the last few weeks, campaign aides and surrogates have been sparring over policy in back-and-forth statements, cable TV appearances, and on social media, but now the candidates will have the chance to speak for themselves on their differences and present their visions for the country.

The second 10 candidates who are set to square off on Wednesday are:

Colorado Sen. Michael Bennet
New York Sen. Kirsten Gillibrand
Former HUD Secretary Julián Castro
New Jersey Sen. Cory Booker
Former Vice President Joe Biden
California Sen. Kamala Harris
Andrew Yang
Hawaii Rep. Tulsi Gabbard
Washington Gov. Jay Inslee
New York Mayor Bill de Blasio

But beyond the two sets of polling front-runners potentially squaring off each night — Sanders, I-Vt., and Warren, D-Mass., sharing center stage on night one, and Biden and Harris on night two — a parade of moderates will have the opportunity to take on the progressive stalwarts. Some occupying the lower fundraising tiers will have the chance to directly confront Biden, even as he prepares for attacks from all sides.

“As the clear front-runner, the attacks will once again be directed Joe Biden’s way,” a senior Biden campaign official told ABC News.

A day prior to the first night of debate, a new Quinnipiac University poll, released Monday, put Biden comfortably back on top of the Democratic field, with 34 percent support and significant distance between him and the next polling tier of Warren (15 percent), Harris (12 percent) and Sanders (11 percent).

While Biden expects attacks from all sides, he said last week at a fundraiser in Michigan that if his 2020 rivals talk about his past, he’ll return the favor and won’t be “so polite this time.”

“As the clear front-runner, the attacks will once again be directed Joe Biden’s way. And our opponents are already telegraphing how they plan to attack him: Bill de Blasio on trade and workers’ rights, Cory Booker on crime bill, Kamala Harris running the same play once again on busing, Gillibrand on women’s rights, Castro on immigration. We’re expecting it, but we’re also expecting the unexpected,” a senior Biden campaign official told ABC News.

Earlier on Monday, Harris said of her debate strategy, “My mother raised me to be polite, and I intend to be polite. I will express differences and articulate them, and certainly point out where we have differences of opinion.”

Two days before Booker is set to take the stage, his campaign team is already eyeing the road ahead.

Campaign officials outlined Booker’s pathway to victory in the general election, announcing they will be rolling out trips to Wisconsin, Pennsylvania and Michigan over the coming days with the hopes to mobilize black voters who may have “stayed home, were discouraged or suppressed” from voting in 2016.

“With more young people and people of color getting inspired as part of the resistance to Trump and the desire for a change in politics as usual, Sen. Booker is uniquely positioned based on his backgrounds and strengths as a candidate to connect with those voters and energize them back into the democratic fold,” said his chief innovation officer Emily Norman.

But his campaign manager, Addisu Demissie, detailed his debate strategy during the Monday call, saying, “I think Cory’s approach to the debate is to be himself. And, you know, that means present his vision for the country, how he’s going to be Donald Trump, and begin the process of fixing and healing, the pain that Donald Trump has caused.”

“‘Be yourself’ is our best advice to him. And when he does that people like him and end up voting for him,” he added.

One lower-polling candidate, de Blasio, is “ready to perform” after a “very good first debate performance,” his campaign team said.

“There are legitimate contrasts between the candidates and their positions in this battle for the heart and soul of the Democratic Party and the mayor is fully prepared to discuss these as well as his long list of accomplishments in New York City,” said Jaclyn Rothenberg, his national press secretary. “The most controversial issue in debate prep so far has been how the Mets got Marcus Stroman and why. With the help of his team, he’s prepared and ready to take the stage on Wednesday to deliver his message of putting working people first.”

For most of the candidates on stage, the stakes for this two-night showdown are much higher after the Democratic National Committee announced more stringent qualifying rules for the September and October debates: candidates will need 2 percent in four qualifying polls and cross the 130,000 donor mark to qualify.

Only seven candidates have qualified for the September debate, according to an ABC News analysis, including Biden, Booker, Mayor Pete Buttigieg, Harris, former Texas congressman Beto O’Rourke, Sen. Bernie Sanders, I-Vt., and Sen. Elizabeth Warren, D-Mass. The rest of the field has only a month to go before the deadline.

These debates in Michigan, the site of the heart of former Democratic nominee Hillary Clinton’s loss in the Midwest after then-candidate Trump carried the state by 0.3 percentage points, also come a week after former special counsel Robert Mueller’s nearly seven-hour testimony on Capitol Hill, when he raised the specter of Russian meddling in the 2020 election, after testifying that 2016 “wasn’t a single attempt … they expect to do it during the next campaign.”

In a new ABC News/Ipsos poll, 54 percent of Americans said that they are not confident in the capability of the U.S. to effectively defend itself from potential foreign government interference in the 2020 presidential election. Only 17 percent said they were very confident and 27 percent were somewhat confident.

But with concerns of foreign interference looming over the field, squabbles continue over the direction of the party. On Monday, the candidates engaged in an early preview of a debate over healthcare, after Harris released her “Medicare for All” plan, an offshoot of the Sanders’ bill he introduced and she co-signed, which includes a loophole to allow private insurers to offer Medicare plans during a 10-year period.

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