In a new op-ed for the Wall Street Journal, one of the Koch brothers -- Charles -- responds to a torrent of criticism from Democrats.

Koch says he and his brother are fighting for a free society, while their opponents prefer big government and "collectivism."

Here's the key part, in which Koch responds semi-directly to Senate Majority Leader Harry Reid's (D-Nev.) repeated criticisms that the Koch brothers are trying to "buy America":

Instead of encouraging free and open debate, collectivists strive to discredit and intimidate opponents. They engage in character assassination. (I should know, as the almost daily target of their attacks.) This is the approach that Arthur Schopenhauer described in the 19th century, that Saul Alinsky famously advocated in the 20th, and that so many despots have infamously practiced. Such tactics are the antithesis of what is required for a free society—and a telltale sign that the collectivists do not have good answers.
Rather than try to understand my vision for a free society or accurately report the facts about Koch Industries, our critics would have you believe we're "un-American" and trying to "rig the system," that we're against "environmental protection" or eager to "end workplace safety standards." These falsehoods remind me of the late Sen. Daniel Patrick Moynihan's observation, "Everyone is entitled to his own opinion, but not to his own facts."

Koch goes on to note that his companies employ 60,000 people and describes various awards they have received for environmentalism, among other things.

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. I believe that cronyism is nothing more than welfare for the rich and powerful, and should be abolished.

Update, 12:35 p.m.

Senate Majority Leader Harry M. Reid (D-Nev.) responded to the Koch op-ed Thursday at an event held to build support for a proposed increase in the minimum wage.

"I think I must be getting under their skin," Reid told the crowd, packed mostly with members of labor unions.

"Most people here are familiar with the Koch brothers. If I've helped make them a little more infamous or famous, I'm glad I've done that. These two men are a pair of shadowy billionaires spending millions of dollars to rig our political system. And who does it help? Them."

Also Thursday, Sen. Jerry Moran (R-Kan.), who chairs the National Republican Senatorial Committee, read Koch's entire op-ed during a speech on the Senate floor and urged his colleagues to read it.

Ed O'Keefe contributed to this story. Originally posted at 8:15 a.m.