Candidates must meet one of three criteria in polls conducted between October 29 and December 13 and recognized by CNN: An average of at least 3.5% nationally; at least 4% in Iowa; or at least 4% in New Hampshire.
The debate is Tuesday, December 15 in Las Vegas, Nevada.
Right now, nine candidates would make cut for the Republican National Committee sanctioned debate at The Venetian in Las Vegas: Donald Trump, Ben Carson, Florida Sen. Marco Rubio, Texas Sen. Ted Cruz, former Florida Gov. Jeb Bush, Ohio Gov. John Kasich, Kentucky Sen. Rand Paul, Carly Fiorina and New Jersey Gov. Chris Christie.
Paul is on the bubble for the debate. He clears the national hurdle of 3.5%, but doesn't average 4% in either of the first two states to vote in the 2016 nominating process.
Christie would make the main debate stage as of Friday -- but he did not qualify in the last GOP debate, hosted by Fox Business Network.
CNN also announced that it, along with Facebook and Salem Media, will hold a second debate for Republican candidates who don't make the cut for the main stage.
To qualify for the earlier debate, candidates must reach at least 1% in four separate national, Iowa or New Hampshire polls that are recognized by CNN.
The network said it will recognize data collected from surveys that began no earlier than October 29, 2015 and are released no later than 9 a.m. on December 13.
Polls that will be considered are live interviewer national and state surveys by: ABC News, Bloomberg News, CBS News, CNN, Fox News, Gallup, Marist University, McClatchy News Service, Monmouth News Service, NBC News, The New York Times, Pew Research Center, Quinnipiac University, Time, USA Today, The Wall Street Journal, The Washington Post, The Des Moines Register, the University of New Hampshire, WBUR and WMUR.
CNN also said Chief Political Correspondent Dana Bash will join conservative talk radio host Hugh Hewitt as questioners in the debate that will be moderated by Wolf Blitzer.
Read the full CNN debate criteria:
UPDATE: This story was updated to reflect the time that surveys will be considered.