With fortunes of $43 billion apiece, Charles and David Koch are fourth on the list of wealthiest Americans. But they are unsurpassed in their influence over vast donor sums discreetly pouring into the country's conservative movement.
Their Koch Industries conglomerate, with interests in chemicals, oil refining and electronics, is the second largest private enterprise in the United States, according to Forbes, with $115 billion in revenue in 2013.
The brothers, who give few interviews, are at the forefront of a network of hundreds of wealthy donors who share the objective of minimizing the role of the federal government, shrinking taxes, eliminating regulations, and generally resisting the policies of Democratic President Barack Obama.
Dozens of conservative organizations have sprung from these donors, who meet twice a year at exclusive summits under the auspices of the Koch-funded organization Freedom Partners.
Candidates for the Republican presidential nomination flock there. According to Charles Koch, the goal is to raise and spend $250 million for the 2016 election cycle -- enough to rival the funds raised by official campaigns.
"It is a better managed use of money," millionaire entrepreneur James Von Ehr II told AFP in an interview, speaking about the donations gathered and spent through the Koch network that he has been a part of since 2009.
"I can tell that Charles is an incredible manager, and his people are excellent people," said Von Ehr, the Texas-based chief executive and founder of the nanotechnology firm Zyvex.
One of the network's most powerful organizations, Americans for Prosperity, was founded in 2004 by the Kochs.
It enjoys a nonprofit tax status that allows it to keep its list of donors anonymous, unlike political action committees that are strictly regulated and must report their donations and names of their contributors.
- Crossing the line -
Officially, these non-profit groups are not supposed to formulate policy, but some have been accused of crossing the line from political advocacy into political activities.
Americans for Prosperity flooded television screens in 2012 with anti-Obama advertising, leading Democrats to denounce such deluges of "dark money" into US politics from billionaires who have everything to gain from tax cuts and the weakening of environmental standards.
The Koch brothers say they want to end corporate welfare and "crony capitalism," and denounce the collusion between government, lawmakers and big business that distorts competition by providing subsidies to well-connected corporations.
The uber-capitalist Koch philosophy has seduced hundreds of conservatives like 65-year-old Von Ehr, a libertarian who stands intensely opposed to "government interference with competition."
He expressed disappointment with the Republican Party, which under George W. Bush's 2001-2009 presidency allowed an explosion of government spending.
Through the Koch network, Von Ehr hopes to boost his funding firepower.
"I spend money to try and elect politicians who won't harass me and won't harass other small businesses and... the cause of freedom," he said.
"The reason we have so much money in politics is because politics has so much power over all of our society," Von Ehr added.
"Everyone wants to protect what they have... I'm trying to protect my individual liberty."
In Von Ehr's case, he wants to protect his company against the corporate favoritism bestowed on other firms.