COLORADO SPRINGS, COLORADO - JUNE 29: Founder of Stand Together Charles Koch and CEO and Chairman of Stand Together Brian Hooks prepare for the Stand Together Summit on June 29, 2019 in Colorado Springs, Colorado. (Photo by Daniel Boczarski/Getty Images for Stand Together)

Billionaire conservative icon David Koch has died at age 79, multiple news sources have reported. The New York resident was suffering from deteriorating health as of late, according to a letter Koch’s older brother Charles Koch sent to company officials last summer.

CBS News reports that Charles Koch wrote at the time: “We are deeply saddened by this, as we miss David’s insightful questions and his many contributions to Koch Industries.”

Charles released a statement on his brother’s passing, saying he will be “greatly missed, but never forgotten.”

Despite donating millions of dollars to Republican organizations, the Koch Brothers did not support President Trump’s 2016 campaign, which, according to Fox News, upset the President. Fox also reports that the Koch Brothers announced that they would not be supporting his 2020 campaign either.