The big news was the departure of California Sen. Kamala Harris , who at one point was seen as having a real chance at the nomination. But Montana Gov. Steve Bullock and former Pennsylvania Rep. Joe Sestak also got out of the race Sunday and Monday.

That sort of rapid winnowing of the field will begin to be the rule, not the exception, as we draw within a few months of the first votes of the 2020 race. We're getting very close to the point where some of the candidates in hopes of having that One Big Moment will need to look at themselves in the mirror and admit that it just ain't happening.

When does that moment come for the 15 men and women still running for the Democratic presidential nominee? It sort of depends on each individual. But the deadline to make the next debate is on December 12 -- and only six people have currently qualified. For the nine who haven't made it, a group that includes well-known figures like New Jersey Sen. Cory Booker and former San Antonio Mayor Julián Castro, missing the debate could be that look-in-the-mirror moment.

Below, the 10 people most likely to wind up as the Democratic nominee for president next year.

10. Julián Castro: Castro is highlighting his status as the lone Latino in the race -- hoping to make inroads with voters looking for a diverse candidate in the wake of Harris' decision to drop out. It's hard to see how Castro can make the December 19 debate, however, and without that sort of platform, how he will find a way to build the momentum he desperately needs to be relevant. (Previous ranking: Unranked)

9. Tom Steyer: This businessman is probably not going to be the Democratic nominee. But he does have two things that not every candidate in the race can count on. First, Steyer's self-funding, so he's not going to run out of money. Second, he's going to be on the debate stage in December, so he can spread his message. About half the field didn't qualify. (Previous ranking: 10)

8. Cory Booker: Booker, like Castro, is placing a big bet on Democratic voters' desire for a diverse candidate with Harris out and all six candidates who have currently qualified for the December debate being white. "There are more billionaires in the race than there are black people," he said Thursday morning. Booker's problem is that his window of relevance is closing rapidly. r: Booker, like Castro, is placing a big bet on Democratic voters' desire for a diverse candidate with Harris out and all six candidates who have currently qualified for the December debate being white. "There are more billionaires in the race than there are black people," he said Thursday morning. Booker's problem is that his window of relevance is closing rapidly. Booker currently has ZERO qualifying polls required to make the next debate -- and exactly one week to get them. Which seems very unlikely. And if he can't make the debate, does he keep going or no? (Previous ranking: 8)

7. Andrew Yang: Yang's support is limited, but it's Yang's support is limited, but it's a solid 2% to 3% . More important, he has shown a true ability to raise mone y. The problem for Yang is that he still needs one more qualifying poll for the December debate, and the debate qualification rules may only get stricter for future debates. For now, he's a niche candidate. (Previous ranking: 7)

6. Michael Bloomberg: Bloomberg has spent north of $57 million of his own money on an opening round of ads aimed at introducing himself to voters in California, Texas and other large population states that are set to vote on Super Tuesday (March 3) or later that month. And if past is prologue, : Bloomberg has spent north of $57 million of his own money on an opening round of ads aimed at introducing himself to voters in California, Texas and other large population states that are set to vote on Super Tuesday (March 3) or later that month. And if past is prologue, there's a lot more money where that first installment came from . (Bloomberg is worth around $55 billion, according to Forbes. ) What remains to be seen is whether Bloomberg's ads -- and the message of business competence and results -- moves voters. And we haven't seen much polling yet that answers that question conclusively. (Previous ranking: 9)

5. Amy Klobuchar: There's a big jump from No. 6 to No. 5 on our list. The senior senator from Minnesota is going to be on the December debate stage, and her November debate performance was There's a big jump from No. 6 to No. 5 on our list. The senior senator from Minnesota is going to be on the December debate stage, and her November debate performance was seen as a success . Klobuchar has risen to fifth place in Iowa and is a wild card in this race. She is someone who could, in theory, be acceptable to most of the party, if she caught fire. Let's not overplay though: she's polling at only about 2% to 3% nationally. (Previous ranking: 5)

4. Bernie Sanders: The Vermont senator has had a bit of a resurgence in recent weeks, taking advantage of some slippage by Massachusetts Sen. Elizabeth Warren. The problem for Sanders is the same problem he's had since he began running for president in 2015: Can he find ways to expand his support beyond his hardcore allies? Because we know that while Sanders may have the most ardent backers, there are simply not enough of them currently to deliver him the nomination. (Previous ranking: 4)

3. Elizabeth Warren: The last month has been rough on Warren. Her Iowa poll lead is gone, and she has fallen into a tie for second place nationally. There are numerous reasons for Warren's drop, The last month has been rough on Warren. Her Iowa poll lead is gone, and she has fallen into a tie for second place nationally. There are numerous reasons for Warren's drop, including attacks on her "Medicare for All" stance. But while there's a lot that has gone poorly, don't lose sight of the topline. Warren is still well-liked by Democratic primary voters and has the most endorsements besides Biden . (Previous ranking: tie for 1)

2. Pete Buttigieg: If the Iowa caucuses were held today, the South Bend, Indiana, mayor would win. And he'd have a pretty good chance of winning the New Hampshire primary eight days later, too. No one else in the current field can credibly make that claim. For Buttigieg, the challenge will be keeping up this momentum all the way through early February when people actually start voting. But he is very much right where he wants to be right now. (Previous ranking: 3)