COLORADO SPRINGS — In 2003, billionaire industrialist Charles Koch gathered a small group of like-minded business leaders to oppose increased federal spending and steel tariffs under the George W. Bush administration.

Koch, 82, is now ringing the alarms again 15 years later at this weekend's meeting, which has grown to include more than 500 major donors to his influential network, amid the brewing trade war under President Trump.

The twice-annual confab kicked off Saturday afternoon with a video message released to reporters in which an impassioned Koch decries protectionism and those who support it.

“They’re doing whatever they can to close themselves off from the new, hold on to the past and prevent change,” Koch says in a video. “This is a natural tendency, but it’s a destructive one because when people act in protectionist ways, they erect barriers, which makes everyone worse off.”

The four-minute video was produced for the three-day gathering at the sprawling Broadmoor resort here and will be broadcast to the mega-donors in attendance, who have each contributed at least $100,000 annually to Koch-linked groups. It will be shown at Koch network events across the country, signaling the seriousness with which the network intends to raise the pressure on the Trump administration over its trade policy.

The video is narrated entirely by Koch, dressed in a light-blue, button-down shirt and a dark-blue blazer, speaking directly to the camera. He describes the beginnings of Koch Industries as historical footage of a younger Koch flashes on the screen, and he credits the growth of his company to “rejecting protectionism for a vision of mutual benefit and continual transformation.”

“When the U.S. has followed this vision, it's succeeded beyond what anyone could have imagined,” Koch says in the video. “And if we remain true to this vision as a network, we will help people improve their lives beyond what any of us can imagine.”

But, he adds, “we face a herculean task. Protectionism is perverting the key institutions of our society. It’s created immense barriers that are holding people back. So if we want to help all people realize their potential, we have to break these barriers.”

The network is undertaking what officials described as “a multiyear, multimillion-dollar commitment” to promote the benefits of free trade.

“The policy response of tariffs in order to achieve anything is absolutely inappropriate policy, and we intend to make that case very strongly to the American people,” said Brian Hooks, a top Koch official. “The policies right now are hurting people, no doubt about it.”

The network’s top officials sharply criticized Trump's plan to provide $12 billion in emergency aid to farmers caught in the trade war, calling it a “bailout of bad policy.”

“We put tariffs, supposedly, to hurt and put pressure on China, and then it actually hurts farmers here,” said James Davis, a Koch network spokesman. “Crops waste away in the field, and then you pull a Depression-era program out to bail out farmers, to make them whole. But who’s underwriting our debt?”

Earlier this year, Koch took aim at Trump’s trade policy in a column that was published in The Washington Post, warning against the “harmful effects” of the administration’s decision to impose steel and aluminum tariffs. Since then, the Koch network has run ad campaigns and mobilized its grass-roots activists across the country to oppose Trump’s push for tariffs.

Officials said the meeting this weekend is the largest summer gathering of like-minded donors, with 135 first-time participants. Among the Republican elected officials in attendance are Sens. John Cornyn (Tex.) and Tim Scott (S.C.), Reps. Marsha Blackburn (Tenn.) and Douglas A. Collins (Ga.), Florida Gov. Rick Scott, Kentucky Gov. Matt Bevin and Nevada Attorney General Adam Laxalt.

The Washington Post and other news outlets were invited to cover portions of the seminar on the condition that donors not be identified without their consent.

James Hohmann contributed to this report.