David and Charles Koch are widely known for their financial support of conservative causes that favor businesses and stricter environmental regulation, according to the New York Times. He'll proceed to function the CEO of Koch Industries and the unofficial face of the community's political efforts.
Democrats have demonized the Koch brothers for their outsized influence in conservative politics over the last decade.
Charles Koch, 82 said he is "deeply saddened" by his brother's retirement, adding that "David has always been a fighter and is dealing with this challenge in the same way".
Americans for Prosperity president Tim Phillips said: "The Trump administration has taken some incredibly positive steps for the American economy, but tariffs will undercut that progress and needlessly hamstring our full economic potential".
The Kochs, who have channeled billions of dollars into conservative causes, kept their distance from Trump during the 2016 presidential election.
The network has clashed with Trump before and the Koch brothers, who each have a net worth of about $47 billion in the Bloomberg Billionaires Index, didn't support him in the 2016 campaign.
Using the money they made from their Kansas-based family business empire, the Koch brothers have created what is likely the nation's most powerful political organization with short- and long-term goals.
David, who was diagnosed with prostate cancer nearly two decades ago, is the executive vice president at Koch Industries. The Koch network has plans to spend up to $400 million on politics and policy initiatives during the 2018 midterm election cycle. His David H. Koch Center at the NewYork-Presbyterian Hospital, which he donated $100 million to, opened in April, and his outpatient cancer center at Memorial Sloan Kettering is on track to open in 2019.
David Koch's departure will change the makeup of one of the most active and well-funded political forces in the country that has been a bulwark in not just supporting but setting the Republican agenda - although not necessarily President Donald Trump's. The longtime philanthropist, who has supported vaunted NY institutions such as the American Museum of Natural History, the Metropolitan Museum of Art and the Lincoln Center, also funded a cancer research institute at MIT and has donated over $700 million to medical causes since his 1992 cancer diagnosis. Clearly he is obtained to be or he would not stay in Manhattan. "His guidance and loyalty, especially in our most troubled times, has been unwavering".
Billionaire donor David Koch has said he is stepping down from his business and political roles over health concerns. "David has never wanted to anything for himself that he hasn't earned, as his sole desire has been to contribute".