This story is being co-published with Frontline, which is also airing a documentary on the group tonight. Check your local listings.

New signs emerged Monday that a controversial nonprofit may have misled the Internal Revenue Service not only about its political activities but also about support from a purported donor.

Western Tradition Partnership, or WTP, sent the IRS a letter in 2008 asking the agency to expedite the group's request for recognition of its tax-exempt status. The letter said that without it, the group's principle donor, Jacob Jabs, would pull a planned grant of $300,000.

But Jabs, who runs Colorado's largest furniture retailer, said on Monday he had never pledged money to the group, and never even been in contact with them until press stories appeared naming him.

"I think they just grabbed my name out of a hat to forward their agenda," Jabs told us. "I know nothing about the group, never heard of them, never have heard of them until the last few days, and I did not, absolutely did not, commit $300,000 to start this company." (Jabs also spoke with the Bozeman Daily Chronicle, again denying any connection to the group.)

Although operating at the state level, WTP has won national attention for its attempts to fight campaign-finance restrictions. It successfully sued to overturn Montana's ban on corporate spending in elections, extending the provisions of the U.S. Supreme Court's Citizens United decision to all states. It has also sued Montana investigators over the state's ruling two years ago that the group is a political committee and should have to report its donors.

Documents obtained by Frontline on WTP offer a rare look into the inner workings of dark money groups, tax-exempt organizations that can accept unlimited contributions and do not have to disclose their donors for political ads.

On Monday, we detailed how some of those documents pointed to WTP actively shaping the campaigns of candidates for state office in Montana. The documents, found in a meth house near Denver by a convicted felon in late 2010, indicate possible coordination between candidates and outside groups. Outside groups and candidates are not allowed to coordinate.

Social welfare nonprofits like WTP are allowed to engage in some political activity, but IRS regulations say they must have social welfare as their primary purpose. ProPublica has extensively reported on how some of these nonprofits, known as 501(c)(4)'s after their section of the tax code, appear to exploit gaps in enforcement between the Internal Revenue Service and election authorities so they don't have to disclose where they get their money.

As ProPublica and Frontline have previously reported, when WTP applied for recognition of its tax-exempt status, the group also told the IRS under penalty of perjury that it would not directly or indirectly attempt to influence elections. Yet even before its application, the group sponsored mailers that criticized politicians in the 2008 Republican primary.

The IRS approved WTP's tax-exempt status three days after it received the group's request for expedited review.

Jabs said he only first spoke with WTP earlier this month, after seeing reports that he was the primary donor. Jabs said he reached a WTP official, Athena Dalton, who signed the IRS letter citing him. According to Jabs, Dalton told him she was WTP's secretary and had been instructed to send the letter by two other WTP officials, Christian LeFer and Dan Reed.

"I did talk to Christian LeFer," Jabs said. "They basically admitted they used me to get their 501(c)(4) status." Jabs said he also contacted Reed, who did not call him back.

In an email responding to a ProPublica question about Jabs, LeFer wrote: "Your facts are wrong, I 'admitted' no such thing; that doesn't even sound plausible. Further, what significance this issue might hold escapes me. I don't discuss donors, and I can see that your story line does not need my help."

Reed did not respond to a phone call.

On Monday, LeFer also confirmed the documents found in a meth house were stolen from his wife's car and belonged to him and his wife, Allison. The documents included material from outside groups and candidates, and communications between LeFer and candidates. There were surveys of candidates by outside groups and drafts and final copies of mailers marked as being paid for by the campaigns.

LeFer, described as WTP's director of strategic programming in memos in 2009, said in an email that the boxes of documents were stolen in Colorado in June 2010.

"These stolen documents appear to be a mix of those from my consulting and volunteer work and from my wife's independently owned and operated mail and printing shop," wrote LeFer, whose wife runs a company called Direct Mail and Communications in Livingston, Mont. "Both my wife and I have scrupulously endeavored to avoid any possibility of illegal coordination.

"The stolen documents, which were in the process of being transferred to storage when the theft occurred, have been mingled to infer that the work of two separate people is in fact the work of one person and therefore improper. This is false." (Here is LeFer's full response.)

Candidates have confirmed that LeFer worked with Direct Mail. They have also said LeFer was an adviser on their campaigns.

There is also other evidence LeFer worked with the firm.

On Tuesday, a woman named Elizabeth Sheron said that when she briefly worked for Direct Mail in 2010, LeFer welcomed her to the company. She provided us a check from Direct Mail and an email from LeFer in which he asked her to elaborate on her abilities and experience. LeFer also wrote that he hoped to increase the membership of one of his social welfare nonprofits to 250,000 people in two years.

Sheron said she did work for Direct Mail, WTP and other related groups. “They kind of had you involved with every project…no matter who was paying you," she said. “I was paid by Direct Mail but I was doing stuff for other groups." Sheron worked there only briefly before quitting.

In an email, LeFer said he didn't think it was useful to try to recall “snippets of information from years back." He said if reporters sent “the entire file of materials you have and you want to discuss at a later time, please do so."

The documents from the meth house eventually landed in the office of Montana investigators, who couldn't do much with them because they couldn't definitively prove they were real, or how they ended up in a meth house.

On Monday, a lawyer for LeFer confirmed them by sending a letter to Montana authorities explaining that the car was stolen from a homeschooling conference in Denver. The lawyer said the documents were stolen property and “evidence regarding the criminal investigation of the car theft in Colorado." The lawyer also said the documents contained sensitive information, and demanded that the documents be turned over to LeFer.

Montana investigators have sealed access to the documents, saying that now that someone has asserted ownership, they are unable to further discuss or release them until a court rules on the matter.

Western Tradition Partnership is now known as American Tradition Partnership. So far this election season, the group has advocated for candidates in Montana's Republican primary, putting out a press release announcing that 12 of those candidates won. It also has launched a newspaper called the Montana Statesman, which claims to be the state's "largest & most trusted news source," to be the state's "only non-partisan newspaper" and to have been founded in 1889.

A second edition of the purported newspaper was mailed to voters in Montana last week. Like the first edition, the 12-page paper contains many articles attacking Steve Bullock, the Democratic candidate for governor who as attorney general fought the partnership's lawsuits against the state. One on the front page accused him of being soft on child molesters.

Other stories attacked the state auditor, a Supreme Court candidate and the secretary of state.

On its website, the group describes itself as a “no-compromise grassroots organization dedicated to fighting the radical environmentalist agenda."

In a statement responding to the story Monday by ProPublica and Frontline, American Tradition Partnership, or ATP, said it had not coordinated with candidates. "I have never met or spoken to virtually all the candidates on the ballot," wrote Donny Ferguson, the executive director of the partnership and the editor of the Montana Statesman, on the Statesman website.

Ferguson also said the law was always on the group's side, and that the nonprofit had always obeyed every applicable law. He denied that the group told people how to vote. “ATP does not, and never will, tell voters which candidates to vote for," he wrote. “ATP speaks on the issues, informing voters where candidates stand and of their public records."

The IRS defines political advertising much more broadly than election authorities, asking whether social welfare nonprofits directly — or indirectly — engaged in campaign activities.