Sen. Reid descended into the rhetoric of conspiracy to describe an off-the-record fundraising conference organized by the brothers last weekend.
"High levels of security, concealment, deception and oaths of silence," Reid said. "That doesn't sound anything like a typical conference. It sounds more like a cult. But instead of being a religious movement or a secret sect, this is a cult of money, influence and self-serving politics. This is the cult of Koch."
Charles and David Koch are the owners of Koch Industries, a highly-successful conglomerate best known for refining and distributing petroleum and chemicals.
The Kochs have devoted a great deal of their fortunes to philanthropic efforts, including over $500 million in medical philanthropy. This year, David Koch announced a $100 million gift for an ambulatory care center in New York.
These alms have earned the brothers no love from Democrats like Reid because they are also heavily involved in libertarian and Republican political causes.
The Kochs' political activity spans decades and one quixotic vice presidential campaign for the Libertarian Party. While most of their efforts have been devoted to bookish free market enterprises like George Mason University's Mercatus Center, they are renowned and reviled for hundreds of millions in activist political spending.
Their network of donors reportedly plans to raise $290 million in the 2014 campaign cycle, mostly for the benefit of Republicans.
As of two months ago, Sen. Reid has referenced the Koch brothers -- and their "immorality," their "radical philosophy," their "lies" and their dreams of "Koch-topia" -- 134 times from the Senate floor. On one occasion, Reid said that the Kochs "are about as un-American as anyone I can imagine."
Senate Democrats recently walked back a proposed constitutional amendment that would restrict the spending and speech of big players like the Kochs by repealing part of the First Amendment. Sen. Dick Durbin, D-Ill., has introduced a less provocative amendment in its place.
*Full disclosure: I have participated in two Koch-funded internships. However, I was not formally initiated into the cult.