"A shadowy organization with ties to the Koch Brothers" spearheaded an anti-net neutrality form letter writing campaign that tipped the scales against net neutrality proponents, according to an analysis released today by the Sunlight Foundation.

The first round of comments collected by the Federal Communications Commission were overwhelmingly in support of net neutrality rules. But a second round of "reply comments" that ended September 10 went the other way, with 60 percent opposing net neutrality, according to the Sunlight Foundation. The group describes itself as a nonpartisan nonprofit that seeks to expand access to government records.

(UPDATE: The 60 percent figure is being disputed by pro-net neutrality groups that organized their own form letter campaigns. The group "Fight For The Future" says that the Sunlight Foundation undercounted the pro comments by at least 500,000. Sunlight posted a response disputing that analysis, saying that Fight for the Future did not account for duplicate comments.)

The Sunlight Foundation used natural language processing techniques to analyze 1.6 million reply comments.

"In marked contrast to the first round, anti-net neutrality commenters mobilized in force for this round, and comprised the majority of overall comments submitted, at 60 percent," the Sunlight Foundation wrote. "We attribute this shift almost entirely to the form-letter initiatives of a single organization, American Commitment, who are single-handedly responsible for 56.5 percent of the comments in this round."

The 1.6 million reply comments analyzed fell short of the 2.5 million comments the FCC said it received, the Sunlight Foundation acknowledged. Based on the files the FCC released, the foundation said it's "reasonably sure that the FCC’s comment counts are incorrect and that our analysis is reasonably representative of what’s there, but the fact that it’s impossible for us to know for sure is problematic." (UPDATE 2 on Dec. 23: The FCC has explained the discrepancy in a blog post.)

We previously wrote about the anti-net neutrality form letter campaign. The Sunlight Foundation describes American Commitment as "a 501(c)(4) social welfare group founded in 2011, [which] has gotten money from and given money to a variety of groups with ties to Charles and David Koch, mega-wealthy siblings who have underwritten many conservative campaigns and candidates."

American Commitment issued a press release celebrating the Sunlight Foundation's findings. “We’re pleased that the Sunlight Foundation is finally confirming that American Commitment and Americans opposed to regulation of the Internet won the FCC comment period. Better late than never,” American Commitment President Phil Kerpen said in the announcement.

American Commitment said it delivered 808,363 comments "opposing any regulation of the Internet." These comments came in at least 30 variations, "many offering wildly different rationales justifying their positions, and taking positions across the political spectrum in their specifics," the Sunlight Foundation wrote. Here is one example:

Dear Mr. Wheeler, As an American citizen, I wanted to voice my opposition to the FCC’s crippling new regulations that would put federal bureaucrats in charge of internet freedom, and urge you to stop these regulations before they’re enacted. If the federal government goes through these plans to regulate the internet, I know that the internet will change -- and not for the better. [ INSERT VARIANT PARAGRAPH COMMENT HERE ] Like many Americans, I believe that the internet should remain free of government control and unnecessary regulation -- just as it has for the last twenty years of unprecedented growth. Please stop the FCC’s dangerous new regulations, and protect the future of internet freedom here in America. Sincerely, [APPLICANT NAME] [APPLICANT HOME ADDRESS]

88 percent of all reply comments appear to be form letter submissions. Pro-net neutrality groups used form letters to help create a majority of their own in the first round of comments, but to a smaller extent. In that first comment period, about 60 percent were form letters. Fewer than 1 percent of first-round comments were clearly opposed to net neutrality, while two-thirds supported a ban on paid prioritization deals in which Internet providers could charge websites or applications for faster access to consumers.

Overall across both rounds, the Sunlight Foundation said it "characterize[d] 41 percent of the total comments submitted as being anti-net neutrality (with the balance being a mix of pro-NN and comments with no clear opinion)."

But evaluating the comments was difficult, especially in the second round. "Some of the new campaigns on the anti-net neutrality side appear to have been crafted to use similar language to the successful pro-neutrality campaigns of the first round, while supporting opposite conclusions, and many non-form-letter comments used talking points from both camps, making their ultimate intents unclear," the Sunlight Foundation wrote.