COLORADO SPRINGS, Colo. (AP) — The conservative Koch brothers are no more — even if they remain a political powerhouse.

The Democrats' super villains for much of the last decade have quietly launched a rebranding effort that may vanquish the "Koch brothers" moniker from American politics. The catalyst came earlier in the year when ailing billionaire conservative David Koch stepped away from the family business, leaving older brother Charles as the undisputed leader of the Kochs' web of expanding political and policy organizations.

There were already few, if any, clearly identifiable links between the Kochs and their most active spinoff organizations such as Americans for Prosperity, Freedom Partners or the LIBRE Initiative. But in the days after the younger billionaire's retreat, company officials quickly began pushing journalists across the country to change references from "Koch brothers" in their coverage to "Koch network" or one of their less-recognizable entities.

Asked about the shift on Saturday, Koch's chief lieutenants explained that 82-year-old Charles Koch was always far more involved with their political efforts than his ailing brother. The elder Koch addressed the shift directly as he welcomed hundreds of donors to an invitation-only summit at a luxury resort in the Rocky Mountains.

"I am not getting weak in the knees. ... Truly I am not," Charles Koch said with a smile. He added: "We're just getting started."

Regardless of its name, the conservative network remains one of the nation's most influential political forces, a conservative powerhouse simultaneously playing the long- and short-game in a way that ensures it will remain a dominant force long after President Donald Trump is gone. And in sharp contrast to the Republican president who is eager to put his name on his accomplishments, the Kochs are happy to do it in the dark.

While much of the network operates out of sight, the Charles Koch Foundation announced Saturday that it would begin publicly posting all multiyear grant agreements with universities. Last year, the foundation gave $90 million for projects on 300 campuses.

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An estimated 500 Koch donors — each having committed at least $100,000 annually — gathered for the weekend "seminar" that featured a handful of elected officials and high-profile influencers. As is customary for the bi-annual meetings, guests were required to give up their cell phones during some presentations. And while The Associated Press joined a handful of media organizations allowed to witness some activities, photos and videos were strictly prohibited.

Florida Gov. Rick Scott and Tennessee Rep. Marsha Blackburn, both Republican Senate candidates, led the list of elected officials on hand. Senate Republican whip John Cornyn of Texas, South Carolina Sen. Tim Scott and Kentucky Gov. Matt Bevin were also on the guest list.

The money behind the Kochs' push to transform education, philanthropy, immigration, health care, tax laws, courts, government regulation, prisons and the economy has long been cloaked in secrecy.

Koch officials have vowed to spend between $300 million and $400 million to shape the 2018 midterm elections. But there's no way to verify how or where the money is spent because most of its organizations are registered as nonprofit groups, which aren't required to detail their donors like traditional political action committees.

While they have long been closely aligned with the Republican Party's far-right flank, they oppose the Trump administration's policies on spending, trade and immigration.

On Saturday, network leaders seized on Trump's push to apply billions of dollars in tariffs on America's top trading partners. The burgeoning trade war has sparked an outcry from business leaders across the nation, and in a new video Charles Koch lashes out at what he calls the "destructive" rise of "protectionism."

Koch official Brian Hooks warned that, on trade and immigration, "the divisiveness of this White House is causing long-term damage."

Democrats who invested extraordinary time and resources into attacking the Koch brothers in recent years concede that, in the era of Trump at least, the billionaire industrialists are no longer the left's No. 1 enemy.

Adam Jentleson, who previously worked for former Senate Democratic leader Harry Reid, said Koch's quiet rebranding effort represents "a small victory."

"Sen. Reid was always very clear that drawing the Koch brothers out of the shadows was a big part of his strategy," Jentleson said. "He thought people deserved to know who was behind the dark money. This seems like a recognition that they're uncomfortable being out front and are scurrying to get back in the shadows."