Questions about the first Democratic presidential debate are swirling ahead of Wednesday's qualifying deadline.

Only 20 candidates will make the stage for the June 26-27 debate, which will be spread out across two days with 10 candidates on each night.

It's unclear who will debate whom, or how the Democratic National Committee (DNC) will make some of its final calls on the placement of candidates. The DNC has not announced when it will disclose the final list of 20 debate participants, but one campaign source said it could come Friday.

The deadline to qualify is midnight Wednesday and candidates have until 11 a.m. Thursday to provide certification to the DNC.

All of this ensures more scrutiny for the DNC, which faced accusations in 2016 of tipping the scales for eventual nominee Hillary Clinton.

The debate will be a critical moment for candidates to make inroads on the frontrunner, former Vice President Joe Biden. The DNC has said it will spread the field out so that higher-polling candidates appear on both nights, and there is no perception of a "junior" debate. That means some top candidates won't have the chance for a face-to-face encounter with Biden.

The candidates who don't qualify will likely find their campaigns on life support, struggling for new donations and media attention in the crowded field of 24 people.

The first debates will air on NBC, MSNBC and Telemundo.

Here's a look at everything we know - and don't know - about how it's shaping up:

Who has qualified?

Twenty candidates are expected to qualify, either by having received donations from 65,000 unique donors in at least 20 states or by reaching 1 percent support in three sanctioned polls.

Fourteen candidates have met both standards, including Biden and the three candidates closest to him in national polls and early voting states: Sen. Bernie Sanders (I-Vt.), South Bend, Ind., Mayor Pete Buttigieg and Sen. Elizabeth Warren (Mass.).

Sen. Kamala Harris (Calif.), who is just behind those candidates in polls, has also met both criteria, as have Sen. Cory Booker (N.J.), Sen. Kirsten Gillibrand (N.Y.), Sen. Amy Klobuchar (Minn.), former Rep. Beto O'Rourke (Texas), former Housing and Urban Development Secretary Julián Castro, Rep. Tulsi Gabbard (Hawaii), Washington Gov. Jay Inslee, tech entrepreneur Andrew Yang and author Marianne Williamson.

They'll likely be guaranteed a spot on the stage and could be joined by six others who have met just the polling threshold: Sen. Michael Bennet (Colo.), former Colorado Gov. John Hickenlooper, former Rep. John Delaney (Md.), New York Mayor Bill de Blasio, Rep. Tim Ryan (Ohio) and Rep. Eric Swalwell (Calif.).

That leaves Rep. Seth Moulton (Mass.), Montana Gov. Steve Bullock, Miramar, Fla., Mayor Wayne Messam and former Sen. Mike Gravel (Alaska) on the outside looking in, unless they meet the polling or fundraising thresholds by the end of the day on Wednesday.

Could that change?

Absolutely.

The DNC has the final say on who qualifies, and while they've announced the outlets who can produce sanctioned polls, the specific polls that will count remain a mystery.

That has already led to some controversy.

Bullock's campaign accused the DNC of a "secret rule change" after the committee announced that it would exclude open-ended polls from the qualification criteria, thereby eliminating a January Washington Post-ABC News poll that showed Bullock with 1 percent support.

Without that poll, Bullock would not qualify for the debate stage. The DNC has said it notified the Montana governor's team in March that the Post-ABC poll wouldn't be included, a statement that Bullock's campaign hasn't denied.

And the DNC is committed to keeping the debate stage at only 20 contenders. That means that if 21 people qualify, tiebreakers will be implemented, potentially bumping someone off the stage.

Priority will go first to those who meet both the fundraising and the polling criteria.

After that, the DNC will rank the contenders by polling average to determine the final spots, with the final tiebreaker going to the candidates with the most individual donors.

Which night will the candidates appear on stage?

The DNC will hold a random drawing on Friday morning at NBC's headquarters at 30 Rockefeller Plaza in New York City to determine where the candidates are placed on stage and which night they'll appear.

It's unclear whether the proceedings will be televised or streamed online, but representatives from the campaigns have been invited to witness the drawing.

To ensure that there is no appearance of an undercard debate, the DNC will divide up the highest polling and lowest polling candidates so that they're evenly dispersed on each night.

The results are expected to be announced shortly after the drawing.

What's next?

The candidates who don't qualify for the first debate will be looking for different ways to stand out, potentially holding their own events around the time of the debate.

However, the candidates who don't qualify won't be able to hold their own debate, as the DNC has instituted a rule saying that if candidates participate in unsanctioned forums they'll be barred from future debates.

The same qualifying criteria - 65,000 donors from 20 states and 1 percent support in three polls - will apply for the second debate, which will take place in Detroit in late July and will be hosted by CNN. The lineup for next month's debates will be announced at a later date.

The DNC will double the thresholds to qualify for the debate after July, requiring candidates to have received 130,000 individual donations and poll at 2 percent in three sanctioned polls.

There has been some griping from the low-polling candidates that the DNC is actively winnowing the field by implementing stringent qualifying thresholds. Some are accusing the national party of putting its thumb on the scale, which echoes allegations from 2016 that the DNC favored Clinton over Sanders.

But national Democrats have largely been supportive of the DNC's efforts so far in handling the massive field of contenders, and many are eager to see the size of the field shrink to a more manageable number.

"People have to demonstrate progress and those that do will stay on the debate stage," DNC Chairman Tom Perez told The Hill in a recent interview. "Those that don't, won't."