The criteria for qualifying for the third debate is as follows:
1) A minimum of 130,000 unique donors with at least 400 unique donors per state in at least 20 states by 11:59pm on August 28th.
2) Polling at or above 2% in four separate polls (from a list of approved polls) published between June 28th and August 28th.
All candidates who qualify for the third debate are automatically qualified for the fourth debate, and any candidates who do not qualify for the third debate may qualify for the fourth debate if they meet both of the above criteria by a new deadline, which will be two weeks before the debate is held in October (exact date TBD). In other words, it's theoretically possible that the fourth debate will actually have more candidates than the third debate.
As of today, these 9 candidates are all officially in:
Joe Biden Pete Buttigieg Kamala Harris Bernie Sanders Elizabeth Warren Cory Booker Beto O'Rourke Amy Klobuchar Andrew Yang
On the cusp:
JuliÃ¡n Castro (donor threshold met, needs 1 more qualifying poll) Tulsi Gabbard (donor threshold met, needs 3 more qualifying polls) Tom Steyer (donor threshold unknown, needs 1 more qualifying poll)
I think Castro will pull it off, but Gabbard is extremely unlikely to hit the polling numbers she needs in time. Steyer is a wildcard, and it really depends on what his donor count is, which is completely unknown at this time. He's very close on the polling, so it's just a matter of finding out where he's at in total donors.
Nobody else has a realistic prayer. So... bye, bye, Kirsten Gillibrand, John Hickenlooper, Michael Bennet, Steve Bullock, Bill de Blasio, John Delaney, Jay Inslee, Wayne Messam, Seth Moulton, Tim Ryan, Joe Sestak, and Marianne Williamson.
Hopefully a half dozen or so of them will drop out right after they're officially disqualified from the debate on August 28th.