(CNN) The Democratic National Committee announced on Thursday which 20 Democratic presidential candidates qualified for the first set of debates, providing clarity to the June matchup that will feature the first high-profile clashes of the party's nominating process .

Those candidates are:

That leaves three Democrats -- Montana Gov. Steve Bullock, Massachusetts Rep. Seth Moulton and Miramar, Florida, Mayor Wayne Messam, a candidate whose campaign has struggled to gain any traction -- on the outside looking in at the first debates on June 26 and 27 in Miami.

Based on public information, it had been clear for days that Bullock, Moulton and Messam were the three candidates likely to miss the debate stage.

And both Bullock and Moulton's campaigns have been resigned that they will not make the first debate.

"No, I'm not going to make the first debate, but I knew that getting in so late," Moulton told Hugh Hewitt earlier this month.

In an interview with CNN on Sunday, Bullock said he was "disappointed" that he was likely to miss the first DNC debate, but said he is "going to keep doing what I'm doing" whether he makes the stage or not.

"We'll still have plans. We'll be meeting voters and if not on that, we'll be doing the things yet," he said. "But, yeah, I'm disappointed."

What remains in question is how the qualifying candidates will be dispersed over the two nights. NBC, the Democratic committee's media partner for the first debate, will make that announcement on Friday, sources tell CNN.

NBC will divide the 20 Democrats vying to take on President Donald Trump into two groups: those with a polling average at 2% or higher and those whose polling average is under 2%.

NBC, according to a DNC aide, will then do a random selection, dividing up the top tier and lower tier into the two nights to ensure an even mix of candidates on each debate stage.

Four sources say the drawing will take place on Friday at Rockefeller Center in New York. Representatives of each of the campaigns that qualified will be allowed to have someone there.

Which candidates end up on the same stage will determine a great deal about the tone and tenor of each debate. Candidates, as the debates loomed, have already signaled a willingness to go after each other on a host of issues, with some of the barbs getting more and more direct.

The most likely recipients of attacks are the two top candidates -- Biden and Sanders -- who have taken fire from a host of lesser known candidates eager to vault themselves into contention by punching up.

Hickenlooper and Delaney have both gone after Sanders from the right, faulting his view of Democratic socialism as out of step with what more Americans want.

"To his credit, Sanders has been consistent in his support for socialism and even, at times, communism," Delaney said in a statement on Wednesday, ahead of a speech Sanders gave on his view of Democratic socialism.

The opposite has happened with Biden, as most competing campaigns have shown a willingness to go after him from the left, questioning his liberal credentials and looking to undercut him with the party's base.

The Sanders campaign has been the most aggressive in criticizing Biden, and a shared debate stage would give the Vermont senator an opportunity to confront the former vice president directly.

But candidates like Buttigieg and Warren also tested out lines at events in June that are clearly -- even if not by name -- aimed at Biden.

Buttigieg, at an event in Iowa earlier this month, said "some of my fellow Democrats... want to see a return to the 1990s or 2000... just as some conservatives want to return to the 1950s."

"That doesn't have to happen," the mayor added in a preview of a "generational change" line Buttigieg could use against the older candidate.

Biden, too, has clearly been testing lines against these critiques.

"I gather some people think that's a return to the past," he said in a recent speech. "I don't see it that way. I see it as embracing the enduring values that have made America -- America."

There are also wildcards in the field of Democratic contenders. Williamson is a largely unknown figure, and Yang, a businessman with a sizable following on line, has shown a willingness to hit hard at people like Biden.

"Joe Biden must really not like to travel," Yang said on Sunday at a Democratic event that brought together 19 candidates. Biden declined the invitation because of his granddaughter's graduation.

Biden responded by saying it shouldn't be surprising that he picked his granddaughter's graduation over the event, saying he would have missed an inauguration to be with his family.

Yang, undeterred and in a sign of what he could do on the debate stage, responded: "Out of 19 presidential candidates in Iowa this weekend, I guarantee you that several were missing family obligations. That's what happens when you run for president. If a front runner says that we have different values that's on him."