Kelly Dittmar, an assistant political science professor at Rutgers University and scholar at the Center for American Women and Politics, tells Bustle that the diversity of the debate stages during the first round affected the perspectives viewers heard, for example when Harris challenged Biden on his record on busing.

"Those stages reflected greater diversity than we've ever seen in terms of race and gender diversity on presidential debates stages," she says. "You hear and see different issues being raised from a different perspective, in part because you have diverse set of voices on the stage."

Jennifer Lawless, a politics professor at the University of Virginia and the former director of the Women & Politics Institute at American University, tells Bustle that race, gender, and identity will be front and center again this week, in part because of the president's rhetoric since the first pair of debates. On July 14, Trump tweeted that minority women in Congress should "go back and help fix the totally broken and crime infested places from which they came." Then, on July 17, Trump attacked Rep. Ilhan Omar (D-Minn.) at a North Carolina rally, with his supporters chanting, "Send her back!"

Then just three days before the second round of debates was to kick off, Trump attacked Rep. Elijah Cummings (D-Md.), a black lawmaker who is the chairman of the House Committee on Oversight and Reform, which is investigating Trump.

"This is going to be an opportunity for Democrats to differentiate themselves from Donald Trump, from his policies, from the kind of language he's been using, but also to demonstrate that they are particularly credible on issues of inclusivity and diversity," Lawless says.

She says the intersection between gender and race could frame a number of broad policy discussions, including about immigration and the economy. Those discussions might not go so well for candidates like Sanders and Biden, she says, both of whom have faced criticism for their records on race. As a result, Lawless says Harris and Warren will have a "little bit of an edge" when policy discussions intersect with race and gender.

When the CNN debate lineups were released, many noted that the Tuesday night lineup features only white candidates. Elyse Shaw, study director at the Institute for Women's Policy Research, tells Bustle that it's unclear how that will impact the discussion, but that it could go one of two ways: The candidates on the all-white panel could make an extra effort to incorporate issues related to diversity into their answers because they're aware of the criticism about diversity, or the debate could totally lack that intersectional discussion altogether.

While the Tuesday night debate will be the first time that Sanders and Warren go head-to-head, it will be the second time that Harris and Biden share the stage. Lawless says viewers can probably expect more fireworks from Biden and Harris, and similar dynamics between Warren and Sanders.

"You've got a situation this time around where two of the four front-runners are facing off against each other both nights," she says. "And there's a woman in each of those contests and a man. I think that there are now opportunities to see how those candidates are going to interact with each other in a way that the first debates didn't really allow."

Additionally, Biden, Booker, and Harris have been sparring over the last week. Biden released a criminal justice reform plan last week, which CNN reports goes "in the opposite direction" of legislation he's supported in the past. At an NAACP gathering on July 24, Booker criticized Biden's plan and called him an "architect of mass incarceration." He said the plan is "an inadequate solution to what is a raging crisis in our country — that we have 5% of the globe's population but 25% of the globe's prison population, we have the overincarceration of low-income folks, veterans folks, addicted folks, mentally ill folks and disproportionally black and brown folks."

Biden quickly responded, criticizing the Newark, New Jersey, police department's practices while Booker was mayor. "His police department was stopping and frisking people, mostly African American men," Biden said, according to CNN.

On the same day, Biden also criticized Harris' Medicare-for-All plan without naming her. But on the eve of the first debate, he formally called out Harris in a campaign press release, saying her health care plan "backtracks on her long-promised — but then-hedged — support of Bernie Sanders' Medicare for All legislation while at the same time committing to still unraveling the hard-won Affordable Care Act that the Trump Administration is trying to undo right now."

The tension between the three will likely be palpable on Wednesday night.

Dittmar notes that debates this early in the campaign are an opportunity for candidates to boost their polling numbers by performing well.

"What we saw from the first debate was that Bernie and Biden didn't see much benefit and, in fact, saw a little bit of a drop in the polls, in part just because they were up in the front," she says. "What I'm always watching for is the trend."

She says she'll be watching for whether Sanders, Biden, Harris, and Castro see a continued trend upward in their poll numbers after the debate. "Who are the candidates that seem to be benefiting most from the debates?" she asks.

Some candidates will also have to continue proving to Democratic voters that they'd be able to beat Trump.

"Whether they are a woman or a person of color or a woman of color, I think they have an additional sort of burden, which is to make the case to voters that they can win this election," Dittmar says. "The debates provide just one forum in which they can sort of further reassure Democratic voters that they're certainly electable and they can just as well stand up against President Trump."

Lawless says it's still early enough for other, lower-polling candidates to try to break out of the field and make their case to voters.

"When you think about the fact that Joe Biden is literally going to be standing in between Kamala Harris and Cory Booker, that affords Cory Booker an opportunity — and maybe a last opportunity — to make a case to the American people," she says. "So my bet is that he'll be more outspoken and he'll be probably a little bit more confrontational than he had been in the previous debate."

"The same is basically true for people like Beto O'Rourke and Pete Buttigieg, who are coming down to the wire now — they've got to see a spike in the polls or consider calling it quits," she adds.

Many of the candidates are still trying to establish name recognition and outline their platforms during these early debates. That, combined with the fact that they have so little time to answer questions on the debate stage, could make it harder for candidates to really engage with certain issues, Shaw says.

Still, Shaw says she'd like to see the candidates discuss equal pay, paid family leave, and affordable child care. "The high cost of child care and the fact that we don't have paid, protected leave are really, really crucial things that I think should be on any sort of economic agenda," she says.

She would also like to see more discussion of climate change as it relates to social and economic policy. The first round of debates focused on climate change for about 15 minutes. Shaw notes that the Institute for Women's Policy Research did a study in 2010 on the effects of Hurricane Katrina on women in public housing, a majority of whom were women of color.

"It's really stark to see how climate change really does impact lower-income communities, which are oftentimes disproportionately people of color and women way more than in any other communities," she says, adding that she'd like to see more discussion of social and economic policy "through a lens of equity and inclusion."