Washington CNN  — 

Former First Lady Nancy Reagan is inviting 16 Republican presidential candidates to participate in the CNN/Reagan Library presidential debate on September 16.

Former Virginia Gov. Jim Gilmore, who participated in the debate of lower-tier candidates last week, has not yet been invited. Candidates must achieve an average of at least 1% of support in three recognized national polls before September 10 to be included in the debate, as well as meeting other criteria.

The top 10 contenders who made it into the primetime Fox News/Facebook debate last week - Donald Trump, Jeb Bush, Scott Walker, Mike Huckabee, Ben Carson, Ted Cruz, Marco Rubio, Rand Paul, Chris Christie, John Kasich – have all been invited as well as six of the seven candidates who participated in the earlier debate: Rick Perry, Rick Santorum, Bobby Jindal, Carly Fiorina, Lindsey Graham and George Pataki.

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The CNN event will be broken into two back-to-back debates with two groups of candidates, unlike the Fox debate in which the two segments were separated by several hours.

“Debates are a crucial part of the election process, and I’m thrilled that so many qualified candidates have the opportunity to be heard at the Reagan Presidential Library,” Reagan, the widow of President Ronald Reagan, said in a press release.

CNN “State of the Union” anchor and chief Washington correspondent Jake Tapper will moderate both groups participating in the debate, which will be held at the Air Force One Pavilion at the Ronald Reagan Presidential Library.

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