Your guide to tonight's Democratic presidential debate

The Democratic presidential candidates take the stage for the second round of debates Tuesday and Wednesday in Detroit. A lot is on the line for the candidates, who have been engaged in back-and-forths over race and health care coming into this round of debates.

On Tuesday, progressives Bernie Sanders and Elizabeth Warren face off for the first time in this campaign. And several other candidates will be scrambling for a breakout night to get back on voters' minds.

Viewers will also see an odd dynamic onstage — by luck of the draw, all the candidates onstage on Night 1 are white.

So what will people be talking about when it's all said and done? Here's a guide to how to watch and what we're watching.

First, key questions (and answers):

When is the debate?

Tuesday night's debate begins at 8 p.m. ET. It's slated to last at least two hours.

Which candidates are onstage Tuesday night?

In order of their placement onstage:

• Spiritualist and author Marianne Williamson

• Rep. Tim Ryan, D-Ohio

• Sen. Amy Klobuchar, D-Minn.

• South Bend, Ind., Mayor Pete Buttigieg

• Sen. Bernie Sanders, I-Vt.

• Sen. Elizabeth Warren, D-Mass.

• Former Rep. Beto O'Rourke, D-Texas

• Former Gov. John Hickenlooper, D-Colo.

• Former Rep. John Delaney, D-Md.

• Gov. Steve Bullock, D-Mont.

How can I watch?

Tune in to CNN, or listen on Westwood One radio.

Now, here are five questions about what we might see in the debate:

1. Will there be any distinctions drawn between Sanders and Warren?

Warren and Sanders are vying for similar voters interested in taking the U.S. in a more boldly progressive direction on everything from income inequality and social justice to health care and student debt. And Warren has been gaining on Sanders in national polls and has even overtaken him on some state surveys.

The Sanders camp has been clear that Sanders will not go after Warren, because he sees her as an ally in implementing progressive change. But they are competing for the same job, so at some point, that stance will likely have to change if Sanders continues to stagnate in the polls. Whenever he's asked to critique Warren, Sanders dismisses the question and points to his long friendship and working relationship with her. Asked on CNN to say something nice about her, his response was somewhat muted:

Will the moderators try to get them to draw distinctions on their polices? There are some differences between them, namely on just how far each wants to go in reshaping the country. Warren wants big structural change but not socialism. Sanders is fine embracing that word. There are also some foreign policy differences that have not been exploited yet in this campaign. Warren talks about how defense-industry moneyed interests shouldn't "own the table"; Sanders has deeper misgivings about how U.S. foreign policy has been conducted over the years and has been hotly critical of Israel, which he has said is being run by a "right wing" and "racist" government.

2. Will some of the air be taken out of Sanders' sails because Biden isn't onstage?

Much of Sanders' criticism in recent weeks has been trained on Biden, who has continued to lead in polls despite a lackluster first debate performance. Sanders has, in fact, likened Biden's health care plan — centered on the existing Affordable Care Act rather than on a national single-payer health insurance program — to President Trump's.

With Biden not on the stage, Sanders is deprived of the chance to swat at Biden face-to-face on that health care plan. His campaign contends that's not a disappointment. "The truth is, these debates are watched by millions of voters and a great opportunity for every candidate to talk to the American people," Jeff Weaver, a senior adviser to Sanders, told NPR's Scott Detrow. "It really doesn't matter" who debates what night, he added. "The lineup's not that important."

Weaver added: "Will he be talking about the important issues that affect people's lives? Yes, I expect he will be talking about that again. ... It's not as easy to write a news story about the n-e-w-s," he noted, mocking post-debate analysis, "but the issues he talks about are issues that affect real people's lives."

Biden may not be onstage, but several others who back similarly moderate health care overhauls will be, including Klobuchar and Hickenlooper. That's a dynamic worth watching, especially since both those candidates need boosts.

3. How is race raised?

Though health care may be a prime issue, race has also dominated the run-up to the debates. The odd dynamic, by luck of the draw, is that all the candidates onstage on Night 1 are white. So how does race come up on an all-white stage?

It's certainly possible, as Buttigieg has been dealing with a controversy over race and police in his hometown, where he's the mayor. And Warren has certainly put forward a comprehensive plan on racial equality and reducing racial differences in maternal mortality rates, for example.

4. Who breaks out?

Looking at who's onstage — Klobuchar, Buttigieg and O'Rourke certainly need breakout moments. Klobuchar, who has a quick wit, admitted after the first round of debates that she held back.

"I had to sit back and say, 'This is the first debate,' " the Minnesota senator said afterward on MSNBC. She noted that she would have liked to have talked more about farm policy and Russian election interference. After former special counsel Robert Mueller's testimony, perhaps there will be opportunities to talk about what the Trump administration is — or isn't — doing to stop current and future foreign interference in elections. Either way, these three need to establish themselves for a national audience.

No two candidates saw faster rises and more mediocre weeks and months after those rises than Buttigieg and O'Rourke. The last round of debates really did nothing to help either of them. That's going to have to change if they want to be seen as serious contenders for the nomination again.

Candidates Kamala Harris and Julián Castro made the most of their first debate performances in Miami, putting them back on the lips of voters in early campaign states. Klobuchar, Buttigieg and O'Rourke need to do the same after these Detroit debates.

Then there's Montana Gov. Steve Bullock. He was left off the stage in the first round of debates, causing controversy. Bullock has made the case that he has been able to win in a red state where Trump did well — and that those rural, right-leaning voters should not be ignored.

So how does Bullock present that message now that he will be onstage? And does it resonate with a Democratic primary base that has been itching for big, bold change with Trump in office, rather than moving rightward in any way?

5. Without hand-raising, will we get answers that are as clear?

The candidates and Democratic National Committee have mandated that after the first round of debates, there will be no hand-raising questions. That may be because some of the topics that candidates raised their hands to favor have been revealed to not be very popular, according to an NPR/PBS NewsHour/Marist poll conducted after the first debates.

The poll tested some of those policies and found, for example, that being in favor of "Medicare for All" as a replacement to the current private health insurance system might be popular with the Democratic base but is unpopular with a general-election electorate — just 41% overall said it is a good idea. Compare that with the 70% who said Medicare as an option while maintaining private health insurance is a good idea.

Being in favor of giving health insurance to immigrants in the U.S. illegally and decriminalizing border crossings are also popular with the base but unpopular with the general-election electorate. So how will the candidates talk about those things? Watch for hedging and equivocation.

Scott Detrow contributed to this report.

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