Conservative mega donor David Koch, who along with his brother Charles has been one of the biggest forces in GOP campaigns this decade, died Friday at the age of 79.

The Koch family has long been involved in right-wing politics: Fred Koch, the founder of Koch Industries and the father of David and Charles, was also a founding member of the anti-communist far-right John Birch Society. In 1980, David Koch ran for office for the first and only time when he became the Libertarian Party’s vice presidential candidate, but the ticket took just 1% of the nationwide popular vote. Four years later, he founded Citizens for a Sound Economy, a political organization that promoted his business-friendly views within the GOP.

The group ended up splintering in 2004, and Koch’s half became Americans for Prosperity. But it was only in 2010, after the U.S. Supreme Court gutted campaign finance laws with their Citizens United decision, that the Koch brothers and AFP became one of the most important players in American politics.

The Koch brothers and their wealthy allies poured untold millions into AFP, Freedom Partners, and other conservative groups, which in turn spent heavily on outside spending to aid Republican congressional candidates. In 2012 alone, 17 groups in the Koch’s network raised $407 million. Democratic campaigns tried to make the Kochs and dark money a major issue in both the 2010 and 2014 elections, but both those cycles still were disasters for Team Blue.