Candidates wave during the first round of Democratic debates in Miami in June. (Brynn Anderson/AP) (Byrnn Anderson/AP)

The second round of Democratic debates begins Tuesday, and it could be a make-or-break moment for a number of presidential candidates. Here’s what you need to know, from how to watch the debates to what to watch for.

How to watch:

Date: Tuesday, July 30 and Wednesday, July 31

Time: 8 p.m. Eastern

Where: The debates will be held in Michigan, a state Trump won by less than half a percentage point.

Why are there two nights? Because there are 20 candidates. Well, there are more than 20 candidates running for the Democratic nomination, but only 20 will be debating. So like last time, 10 candidates will debate on the first night and 10 on the second.

Who’s on which stage?

July 30 debate — order on stage

Ryan

Klobuchar

Buttigieg

Williamson

Warren

O’Rourke

Sanders

Hickenlooper

Delaney

Bullock

July 31 debate — order on stage

Castro

Bennet

Gillibrand

Booker

Yang

Biden

Harris

Gabbard

de Blasio

Inslee

Note: Wayne Messam, Seth Moulton, Joe Sestak and Tom

Steyer did not qualify for the second debate.

Source: CNN

SHELLY TAN/THE WASHINGTON POST

July 30 debate — order on stage

Williamson

Ryan

Klobuchar

Buttigieg

Sanders

Warren

O’Rourke

Delaney

Hickenlooper

Bullock

July 31 debate — order on stage

Gillibrand

Castro

Booker

Biden

Bennet

Inslee

de Blasio

Harris

Yang

Gabbard

Note: Wayne Messam, Seth Moulton, Joe Sestak and Tom Steyer did not

qualify for the second debate.

Source: CNN

SHELLY TAN/THE WASHINGTON POST

July 30 debate — order on stage

Williamson

Ryan

Buttigieg

Klobuchar

Sanders

Hickenlooper

O’Rourke

Delaney

Warren

Bullock

July 31 debate — order on stage

Bennet

Biden

Castro

Gillibrand

Booker

Yang

Harris

Gabbard

Inslee

de Blasio

Note: Wayne Messam, Seth Moulton, Joe Sestak and Tom Steyer did not qualify for the second debate.

Source: CNN

SHELLY TAN/THE WASHINGTON POST

July 30 debate — order on stage

Ryan

Klobuchar

Buttigieg

Sanders

Warren

O’Rourke

Delaney

Bullock

Williamson

Hickenlooper

July 31 debate — order on stage

Bennet

Gillibrand

Castro

Booker

Biden

Harris

Yang

Gabbard

Inslee

de Blasio

Note: Wayne Messam, Seth Moulton, Joe Sestak and Tom Steyer did not qualify for the second debate.

Source: CNN

SHELLY TAN/THE WASHINGTON POST

July 30 debate — order on stage

Ryan

Klobuchar

Buttigieg

Bullock

Williamson

Warren

O’Rourke

Delaney

Hickenlooper

Sanders

July 31 debate — order on stage

Gabbard

Inslee

Yang

Castro

Booker

Biden

de Blasio

Bennet

Harris

Gillibrand

Note: Wayne Messam, Seth Moulton, Joe Sestak and Tom Steyer did not qualify for the second debate.

Source: CNN

SHELLY TAN/THE WASHINGTON POST

Who are the moderators? CNN’s Dana Bash, Don Lemon and Jake Tapper. (Side note: The Democratic National Committee has asked the TV channels hosting the debates to have a female moderator and a person of color moderating.)

Where can I watch? CNN and CNN en Español will broadcast it. But if you don’t have cable, you can stream it on CNN.com or CNN’s app.

How will the questions be decided? CNN said it and the Democratic National Committee will be “casting wide nets to gauge voters’ concerns and interests."

What are the rules? Candidates will be given 60 seconds to answer a question from the moderator, then have 30 seconds for any follow-ups — like if another candidate attacks them by name. CNN says, unlike in the last debate, there will be no show-of-hands questions. And they warn candidates that if they frequently interrupt, they’ll have subsequent talking time reduced.

When are the next debates? Sept. 12 and 13. The debate stage could look much different then. The Democratic National Committee has doubled its fundraising and polling requirements for the September and October debates, and candidates such as Sen. Kirsten Gillibrand (D-N.Y.) are trying to meet those so they can get on the stage.

What to watch for:

Does Kamala D. Harris build on her momentum? The senator from California was the breakout star of the first rounds of debates for attacking Biden for his position on busing. She’s since risen in the polls. How does she continue her momentum? On Monday, she released a health-care plan that would allow private insurers to sell a Medicare plan to all Americans, instead of getting rid of private insurance like some of her opponents want to do.

Does Biden get more feisty? At one point in the first debate, Biden seemed to run out of steam to defend himself against Harris. Since then on the campaign trail, he’s starting to get more aggressive in touting his work under the Obama administration and criticizing his fellow 2020 Democrats, most recently Harris’s Medicare-for-all plan and the record on criminal justice of Sen. Cory Booker (D-N.J.) when he was a mayor in New Jersey. “I’m not going to be as polite this time,” he told donors.

What does Sen. Bernie Sanders (I-Vt.) do? He also had a relatively uneventful first debate, relegated to the background for much of the fighting between Harris and Biden about race. Does Sanders, who is slipping in polls, find a way to inject himself into any back-and-forths that aren’t about health care or economic inequality?

Who has a breakout moment? Harris showed they are possible, even with 20 candidates spread out over two nights. And we know the top tier of candidates is beginning to be more defined, based on fundraising numbers that came out in mid July. It consists of: Biden, Sen. Elizabeth Warren (D-Mass.), Sanders, Harris and South Bend, Ind., Mayor Pete Buttigieg. Can anyone else — say Booker or Sen. Amy Klobuchar (D-Minn.) — use the debate stage to vault themselves into this tier? Booker will be standing next to Biden and has sharply criticized Biden for Biden’s tough-on-crime record in the ’90s. And what about Montana Gov. Steve Bullock (D), who will be on the debate stage for the first time, since he didn’t qualify for the first round?

Who drops out after this? After the first debate, Rep. Eric Swalwell (D-Calif.) became the first candidate to quit. He frequently tried to interrupt Biden and tell him to “pass the torch” — but Swalwell didn’t generate enough money from that performance to keep going. Other candidates could rely on the second debate for their do-or-die moment. Beto O’Rourke, a former congressman from Texas, had weak fundraising numbers this spring, for example.

Correction: The second debates are broadcast on CNN en Español, not Telemundo.