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The first official Democratic presidential primary debate starts Wednesday, and it’s a big deal for the 20 candidates who qualified to be on the debate stage.

“You get one chance to make a good first impression,” said Democratic strategist Mary Anne Marsh.

Here’s how to watch the debate, from how to watch to what to watch.

When is the Democratic debate?

Date: June 26 and June 27

Time: 9 p.m. to 11 p.m. Eastern time

Where: The debates will be held in Miami, but you were probably asking where on the TV you can watch it. The answer: NBC, MSNBC and Telemundo.

Why are there two nights? Because so many candidates qualified for the debate thresholds, the Democratic National Committee split them up between two nights, with 10 candidates on each stage. Most candidates are randomly selected for each stage, but the DNC spread out the top-polling candidates between the two stages.

Who’s on which stage?

Here’s what the stages will look like:

Who are the moderators? “Today” co-anchor Savannah Guthrie, “NBC Nightly News” anchor Lester Holt, “Meet the Press” moderator Chuck Todd, “The Rachel Maddow Show” host Rachel Maddow and “Noticias Telemundo” anchor José Diaz-Balart.

How will the questions be decided? That will be up to NBC. They are soliciting questions from people here.

What are the rules? Each candidate will have 60 seconds to answer a question and 30 seconds for a follow up. There will be no opening statements but candidates can give a closing statement.

When are the next debates? July 29 and 30. A governor who missed the qualifications for this week’s debates, Montana Gov. Steve Bullock (D), announced he qualified for the July debates. There will be 12 Democratic primary debates overall, six in 2019.

What to watch for

1. Is anyone going to have a breakout moment? Is one even possible? The debate will be unruly: Twenty candidates and five moderators will be spread over two nights. The current leaders in the polls aren’t even on the same stage. And each candidate only has 60 seconds to answer a question. The closest precedent to this is the early 2016 Republican primary debates, in which the top 10 candidates were invited to a main debate and there was an “undercard” debate earlier in the day. There was a lot of back-and-forth, even some shouting. In the end, one person dominated — and that person is now president.

2. Does Joe Biden engage with the other candidates? The former vice president has been running his race as if he’s already the nominee. He’s not schmoozing nearly as much as the other candidates on the campaign trail, which he can afford to do because he’s leading in every major poll. But for at least one night, he’ll be sucked back into the primary for this debate, with a target on his back. Speaking of ...

3. How does everyone else go after Biden? One way to get yourself heard is to draw a contrast with Biden — maybe even draw blood from him, says Marsh. That may have begun. On Wednesday, Sen. Cory Booker (D-N.J.) said Biden should apologize for touting Biden’s work with segregationists. Biden said Booker should apologize. Biden and Booker will debate on different nights, but it’s a safe bet that Biden’s Thursday night opponents will bring up the controversy.

“At some point, the debate is going to get much sharper,” said Democratic strategist Jim Manley. Did that just happen? How will this manifest in the debate?

4. How do all the women onstage change the dynamic? This field is one of the most diverse in history. Six of the 20 candidates in the debate will be women, a first for any major party. Do they talk about their gender, even own it, in a way female politicians haven’t in the past? How could their presence trip up any of the men or moderators?

5. How do the most successful candidates contrast themselves with Trump? Who’s most electable against Trump is a thick undercurrent in the Democratic primary. “Electability” is a subjective (and at times, gender-biased) term that voters are wrestling with. To that end, every candidate is going to want voters to imagine they’re debating Trump — not other Democrats — onstage. There’s no consensus on how to successfully do that. Biden is already talking about Trump by name more than most candidates, but does he respond to Trump calling him “the weakest mentally,” for example? Do the candidates try to focus heavily on policy rather than personality and just ignore Trump? Do they underscore their contrasts? Some candidates are signing onto a pledge not to use stolen information in their campaigns, for example. And how does all of this play into the broader Democratic debate about how antagonistic to be toward Republicans?

President Trump criticized Democratic presidential candidate Joe Biden ahead of his trip to Iowa on June 11. (The Washington Post)

6. How many times is “socialist” mentioned? Another defining debate of the Democratic Party is whether it’s moving too far left (by proposing government-run policies like Medicare-for-all), or whether that’s exactly what needs to happen to beat Trump. Jim Kessler, a Democratic strategist with the centrist Third Way think tank, suggested keeping an eye on whether candidates use the term as an epithet or a point of pride.

7. How negative does Bernie Sanders go? A couple of strategists mentioned to me that if any candidate is going to take his or her gloves off, it’s likely to be Sanders. He is not a conciliatory politician by nature. He’s already gone after Biden. But we may see Sanders on the defensive, too. In the 2016 primary, Hillary Clinton largely avoided attacking him. Given he’s second, behind Biden, in many polls, we could witness Sanders on the defensive for the first time.