(WASHINGTON) — Democrats vying for the White House in 2020 are entering a new phase of the election cycle as the primary season deepens ahead of the third Democratic debate. The first two rounds of debates earlier this summer were critical paths to breaking out from the pack before millions of voters. Now, the third face-off, with more stringent qualifying rules, will perhaps be an indication of the candidates with staying power in the grueling marathon primary.Here’s what you need to know about the upcoming September debate:When is the third DNC debate?The third Democratic primary debate, hosted by ABC News in partnership with Univision, is slated for Sept. 12, and, if necessary, Sept. 13 in Houston. The upcoming matchup will take place at the Texas Southern University, a public, historically black university, and will air across ABC, Univision with a Spanish translation, locally on KTRK-TV, and on ABC News Live.The streaming channel is available on the ABCNews.com website and apps, as well as Hulu Live, The Roku Channel, Facebook Watch, Apple TV, Amazon Fire TV, YouTube, Apple News and Twitter.How do candidates qualify for the third debate?The Democratic National Committee announced more rigorous qualifying rules earlier this year for the fall debates in September and October: Candidates must cross both the polling and grassroots funding thresholds.In order to qualify, candidates must reach 2% or more in at least four national polls or polls conducted in the early voting states of Iowa, New Hampshire, South Carolina and/or Nevada and publicly released between June 28 and Aug. 28. Candidates are also required to receive donations from at least 130,000 unique donors over the course of the election cycle, with a minimum of 400 unique donors per state in at least 20 states. Qualifying donations and polls must be received by 11:59 p.m. on Aug. 28 for the September debate.Any candidates’ four qualifying polls must be sponsored by one or more of the following organizations approved by the DNC: The Associated Press, ABC News, CBS News, CNN, the Des Moines Register, Fox News, Monmouth University, NBC News, The New York Times, National Public Radio, Quinnipiac University, University of New Hampshire, The Wall Street Journal, USA Today, the Washington Post or Winthrop University. They also must be conducted by different organizations or — if by the same organization — must be in different geographic areas.Will the debate be one or two nights?If 10 or fewer candidates are certified by the DNC to participate, the debate will take place on one night.If more than 10 candidates qualify under the rules, the debate will take place over two nights. For the two-night scenario, ABC News in accordance with the DNC will hold a selection event on Aug. 29 to randomly assign the candidates to a night.Who is qualified so far for the third debate?So far, 10 candidates have qualified for the September debate, according to an ABC News analysis of publicly released information and pending verification by the DNC after the qualifying deadline, including:

Former Vice President Joe Biden
New Jersey Sen. Cory Booker
South Bend, Indiana, Mayor Pete Buttigieg
Former Housing and Urban Development Secretary Julián Castro
California Sen. Kamala Harris
Minnesota Sen. Amy Klobuchar
Former Texas Rep. Beto O’Rourke
Vermont Sen. Bernie Sanders
Massachusetts Sen. Elizabeth Warren
Entrepreneur Andrew Yang

Who could be left off the stage?More than half of the crowded Democratic field will be left off stage with the more stringent qualifying rules, and three candidates — Massachusetts Rep. Seth Moulton, Washington Gov. Jay Inslee and Colorado Gov. John Hickenlooper — having dropped out of the race in the weeks leading up to the deadline.According to an ABC News analysis, California activist Tom Steyer and Hawaii Rep. Tulsi Gabbard have already met the donor threshold and are closing in on the polling threshold. Their inclusion would increase the number of qualifying contenders and separate the field over two nights. Steyer needs one more poll and Gabbard is two polls short. Motivational speaker Marianne Williamson has met the donor count threshold, but still needs three more qualifying polls.Colorado Sen. Michael Bennet, Montana Gov. Steve Bullock, New York Mayor Bill de Blasio, former Maryland Rep. John Delaney, New York Sen. Kirsten Gillibrand, Miramar, Florida, Mayor Wayne Messam and Ohio Rep. Tim Ryan are all in danger of not participating in the September debate, since they have not met either the donor threshold or the polling requirement.When will the finalized list of participants be announced?Candidates have until Aug. 28 to qualify and the DNC will officially announce the list of participates for the September debate on Aug. 29. More details about the format and the lineup for the debate will be announced Thursday.Who is moderating the third debate?Chief Anchor George Stephanopoulos, World News Tonight Anchor David Muir, ABC News Correspondent Linsey Davis and Univision Anchor Jorge Ramos will moderate the debate on Thursday and, if necessary, Friday.What is the format for the third Democratic debate?The presidential hopefuls will have one minute and 15 seconds for direct response to questions from the moderators and 45 seconds to respond to follow-up questions and rebuttals.Copyright © 2019, ABC Radio. All rights reserved.