ThinkProgress today accused the U.S. Chamber of Commerce of orchestrating a campaign to discredit its opponents, an alleged plot that the business trade group denies.

In a lengthy post on its website, ThinkProgress describes a labyrinthine effort involving the chamber, its law firm Hunton & Williams, and three private security firms. ThinkProgress contends that the private security companies worked on a proposal to gather information and develop a smear effort against ThinkProgress, Chamber Watch, Change to Win, StopTheChamber.com and Service Employees International Union.

ThinkProgress -- a project of the Center for American Progress Action Fund -- posted links to e-mails and other documents that it said verify the scheme.

The U.S. Chamber rejected any connection to the maneuvers laid out by ThinkProgress.

"We're incredulous that anyone would attempt to associate such activities with the Chamber as we've seen today from the Center for American Progress," Tom Collamore, senior vice president of communication and strategy, wrote on the chamber's website. "The security firm referenced by Think Progress was not hired by the Chamber or by anyone else on the Chamber's behalf. We have never seen the document in question nor has it ever been discussed with us."

"No money, for any purpose, was paid to any of those three private security firms by the Chamber, or by anyone on behalf of the Chamber, including Hunton and Williams," Collamore said.

"The Center for American Progress and its blog, ThinkProgress, disagree with the Chamber's policy stances and are perpetrating a smear campaign by trying to create the illusion of a connection," Collamore added.

Among the leaked e-mails posted by ThinkProgress, a few showed what appeared to be a research effort that involved searching social network sites like Facebook and acquiring information about employees of the liberal groups and their spouses, children and religious affiliations.

"This tactic of targeting opponents' personal lives and family was not simply a random event," ThinkProgress said in its Web post. "Rather, it was a concerted and deliberate effort to use anything possible to smear the Chamber's political opponents."

ThinkProgress said that the leaked e-mails it acquired "are available widely on the web" and were posted by members of "Anonymous," which ThinkProgress describes as an activist community "responsible for taking down websites for oppressive regimes in Tunisia, Egypt, and American corporations that have censored WikiLeaks."

The campaign was headed by Hunton & Williams, ThinkProgress alleged. The chamber last year paid that firm more than $1 million, according to the trade group's form 990 tax return. That document indicates that payment was for "legal services."

Hunton & Williams did not immediately respond to request for comment.

The law firm allegedly negotiated with firms HBGary Federal, Palantir and Berico Technologies, which ThinkProgress said were collectively called Team Themis.

The chamber said that it "never hired or solicited proposals from HBGary, Palantir or Berico, the security firms being talked about on the web."

"HBGary's proposal, which has been written about by ThinkProgress, was not requested by the Chamber, it was not delivered to the Chamber, and it was never discussed with anyone at the Chamber," Collamore said. "The leaked e-mails appear to show that HBGary was willing to propose questionable actions in an attempt to drum up business, but the Chamber was not aware of these proposals until HBGary's e-mails leaked."

Berico Technologies and Palantir in posts on their websites said they had cut ties with HBGary. The Berico post refers to a campaign involving a law firm but did not name the chamber or Hunton & Williams.

"Late last year, we were asked to develop a proposal to support a law firm," the Berico post said. "Our corporate understanding was that Berico would support the firm's efforts on behalf of American companies to help them analyze potential internal information security and public relations challenges.

"Consistent with industry standards for this type of work, we proposed analyzing publicly available information and identifying patterns and data flows relevant to our client's information needs," the Berico post added. "Any subsequent discussions or proposals that attempted to extend the initial scope of work run counter to our organization's values."

Berico said that it was "conducting a thorough internal investigation to better understand the details of how this situation unfolded and we will take the appropriate actions within our company."

The plot allegedly would have two parts. The first involved information gathering and would cost $200,000, ThinkProgress said. Part two would cost $2 million and would include subterfuge to discredit groups like Chamber Watch.

ThinkProgress posted a memo it said was from Team Themis, which outlined the proposal.

According to that memo, Team Themis would "create a false document, perhaps highlighting periodical financial information, and monitor to see if US Chamber Watch acquires it. Afterward, present explicit evidence proving that such transactions never occurred.

"Also, create a fake insider persona and generate communications with [Change to Win]," the document adds. "Afterward, release the actual documents at a specified time and explain the activity as a [Change to Win] contrived operation. Both instances will prove that US Chamber Watch cannot be trusted with information and/or tell the truth."

Click here to read the full ThinkProgress report.