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INDIAN WELLS , CALIFORNIA — Deep in the California desert in an area dotted with luxury homes and golf courses, wealthy conservative activist Charles Koch encouraged the 500 wealthy attendees to his biannual retreat to "be open" about their beliefs.

"I'm kind of incognito, but I’ve been identified lately. It’s not so bad. I’m still here," said Koch, the multibillionaire who has spent an unknown and untraceable amount of money to steer American policy and politics toward a smaller government and a free market.

"Come out and identify yourself, because this isn’t some secret cabal," Koch said during his opening remarks at a cocktail reception at a ritzy golf resort near Palm Springs.

Charles Koch stands for a portrait on Aug. 3, 2015. The Washington Post / The Washington Post/Getty Images

"We have ideas that will make America better and we need to share them, and we need to stand up and be open that this is what we believe because we’re ... making America better," Koch said.

Koch, along with his brother David, host a gathering known as the "seminar" where members and potential-members of their large donor network meet to discuss a political and policy agenda for the years ahead.

Organizers say this is the largest conference yet, with 500 participants — of which one third are in attendance for the first time. A $100,000 entry fee is required to become a member.

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The resort holding the gathering is closed to the public during the three-day event. It includes small break-out sessions, forums and a pledge session where donors indicate how much more they are willing to contribute to the cause.

The Kochs, who have made billions in oil refining and other businesses, have come under fire in recent years for spending large amounts of money on advocacy, outreach and politics under complete secrecy.

While Koch encouraged attendees to speak out, there’s no sign that the multi-faceted organization will stop operating under a component of the tax code that prevents donors from being identified.

Groups under the Koch umbrella engages key constituencies, trains political candidates, mobilizes volunteers to push policy, gives grants to like-minded groups and supports political candidates.

This is only the second seminar that has allowed members of the media. A small number of journalists were invited to cover the event. Six journalists, including NBC News, accepted in exchange for following some guidelines including preserving participants' identity. Attendees are able to speak to the press if they choose.

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The network decided that it would spend $889 million during 2015 and 2016 on their political and policy agenda. It has already spent nearly half of that — $400 million — in 2015, but not on the presidential election.

While the network as a whole has not yet engaged in presidential politics (although individual donors have), a critical topic this weekend among the attendees is sure to be the election. The Kochs are not keen on a Donald Trump nomination.

As Koch encouraged openness for his guests, an opening panel discussion focused on the First Amendment followed a catered dinner in a large ballroom.

Legal commentator Jeff Rosen moderated the discussion that featured Nebraska Sen. Ben Sasse and attorney David French, who specializes in free speech cases.

The opening of the talk showed a video of a protest at Yale from the fall and criticized the idea of "safe space" from offensive speech.

"Continue to speak freely," French said. "If the leaders are afraid then everyone will be afraid. So be not afraid."