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PALM BEACH, Fla. — As President Donald Trump was preparing for his trip to Vietnam this past weekend, some of his most loyal supporters gathered Saturday night at his private Mar-a-Lago club, a place generally not friendly to the media.

NBC News got a rare look inside the opulent and sprawling mansion where the president has visited 20 times since his election at a cost of millions to taxpayers.

Decked out in red, white, and blue, and cowboy gear, more than 800 Mar-a-Lago members and guests mingled at the estate for the "Country Comes to Mar-a-Lago" gala hosted by a group of ardent female supporters who refer to themselves as "Trumpettes."

The founding Trumpettes with president Toni Holt Kramer, second from left, at Mar-A-Lago. NBC News

The country extravaganza was orchestrated by longtime Mar-a-Lago member, Trumpette founder, and personal friend of the president's Toni Holt Kramer.

"l love horses and I love cowgirls and I love cowboys, and I have a home in the desert so I'm used to that western look — I thought why not bring country to Mar-a-Lago?" Kramer told NBC News in an interview midparty.

She arranged for the White House to produce a video of Trump addressing her guests with a cozy message.

"We are a very special group of people and you are a very special group of friends. Enjoy your evening in Palm Beach, enjoy your evening at Mar-a-Lago," Trump said in the video projected onto large white screens put up around the extravagant ballroom decked out with 16 crystal chandeliers and gold leaf on the walls. (The ballroom's entrance is just steps away from Trump and his wife Melania's quarters on the property.)

In the video, Trump lauded what he characterized as his success with North Korean negotiations. "Now there's no more rockets going off, there's no more missiles, there's no more nuclear testing... let's see how we do on Monday and Tuesday and Wednesday, it'll be very interesting."

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Earlier in the evening, a small group of partygoers chanted "build the wall" while gathered around a crystal-blue outdoor pool. "I want the wall because I think that the people in Mexico are taking advantage," said attendee Irwin Bruner, born in Panama but raised in the U.S.

The president's son Eric Trump attended as a guest of honor. He and his brother Donald Jr. run the Trump family business including Mar-a-Lago, which costs $200,000 to join and $14,000 per year to maintain a membership. Both Eric and Donald Jr., like their father, have frequently attacked the media. But Saturday night Eric Trump briefly spoke to NBC News before rushing off: "It's an amazing event — a lot of passion and they do a great job so this is exciting."

Tickets for the event ranged from $20,000 for a table of 12 including "elite VIP reception with celebrities, premium seating" to $550 for a single seat. The proceeds went to cover the cost of the party.

Kramer said she spared no expense. "It's a party for the president. The president would never do a party that wasn't the best," she said.

The night featured entertainment by Grammy award-winning musician Lee Greenwood and the Philip Harari Cowboy & Cowgirl Orchestra. Speakers included Fox News personality Jeanine Pirro and actor Jon Voight.

Commerce Secretary and Mar-a-Lago member Wilbur Ross was dining on the terrace and stopped by for photos with a member of the Trumpettes.

Secretary of Commerce Wilbur Ross and Nicole DiCocco at the "Country Comes to Mar-a-Lago" gala. NBC News

Trump's properties have been a source of great controversy since he announced his bid for the presidency, with ethics watchdogs raising concerns that individuals with the means to buy memberships and condos might be using money to buy access to the man who holds the country’s highest office.

The president's use of Mar-a-Lago as a venue for hosting foreign leaders has also drawn scrutiny over potential national security risks.

In February 2017, Trump entertained Japanese Prime Minister Shinzo Abe at his Palm Beach estate following a meeting at the White House. During dinner together, North Korea successfully launched a ballistic missile apparently timed to coincide with the two leaders' summit. Abe and Trump chose to stay seated on the club's terrace while aides huddled around them to strategize. Club members and guests posted pictures of the event unfolding.

That February 2017 incident triggered demands by Democratic lawmakers for a U.S. Government Accountability Office study of the security vetting procedures and secure areas at Mar-a-Lago.

Two months later Trump welcomed Chinese President Xi Jinping to Mar-a-Lago for a two-day summit on North Korea and trade. In the midst of summit meetings, the president made the decision to launch a missile strike in Syria after a deadly chemical weapons attack by Syrian President Bashar al-Assad killed dozens of civilians earlier that week.