In an op-ed piece in the Wall Street Journal, Koch said his life has been shaped by "the principles of a free society." He said he has been the target of "almost daily attacks" by opponents engaged in "character assassination."
"Unfortunately, the fundamental concepts of dignity, respect, equality before the law and personal freedom are under attack by the nation's own government," Koch said. "That's why, if we want to restore a free society and create greater well-being and opportunity for all Americans, we have no choice but to fight for those principles."
Charles Koch is the chairman and chief executive officer of Koch Industries, the second-biggest family owned company in the United States. His younger brother, David, is executive vice-president.
Both brothers, and two others not involved with the company, are known as generous philanthropists. But in recent years, Charles and David Koch have also become known for bankrolling conservative organizations, notably Americans for Prosperity.
Charles Koch defended both his company, which he said employs 60,000 people in the U.S., and his other activities. He said Koch Industries was the only ethanol producer to support ending the ethanol tax credit.
"Far from trying to rig the system, I have spent decades opposing cronyism and all political favors, including mandates, subsidies and protective tariffs -- even when we benefit from them," he said.
“I think I must be getting under their skin,” Reid said. “They wrote an op-ed in the Wall Street Journal telling everybody I was a collectivist, which is code word for you-know-what.”