During the summer of 2005, Don Zimmerman was busy mustering his best Rep. Ron Paul (R-Texas), channeling the libertarian folk hero while trying to lock in an Austin, Texas-area state legislative seat. Pleased with Zimmerman’s anti-tax fervor, Paul nodded in approval and cut the candidate a $1,000 check out of his political action committee that summer.

Zimmerman went on to lose narrowly in the GOP primary. Still, Paul’s support appears to have christened a game of political back-scratching between the two that may test whether sometimes square-pegged, grass-roots political supporters fit into round-holed federal election laws.

A new political action committee that Zimmerman started joins a growing list of shadowy political groups run by activists that — consciously or not — may run afoul of federal law, causing headaches for candidates piling up legal bills in the process.

Since Paul declared as a presidential candidate in February, Zimmerman has become one of his most devoted supporters. At times a paid fundraiser, campaign blogger and Internet organizer for Paul’s presidential bid, Zimmerman appears to have straddled a blurry line between actual employment and true-believing volunteer.

Both Zimmerman and Paul’s presidential campaign deny the activist has any formal role with the campaign, but research by Roll Call suggests otherwise. According to campaign finance records and state corporate records, Zimmerman’s various companies have received almost $25,000 in fundraising fees from Paul’s campaign. Zimmerman also confirmed that he placed advertising and sent out direct mail related to his fundraising events for Paul.

Paul spokesman Jesse Benton called Zimmerman “an independent supporter” and said he no longer has a fundraising contract with the campaign. Zimmerman declined to answer follow-up questions from Roll Call.

“We let him do two fundraising events, a rally in Austin and San Antonio,” Benton said. “He’s been a supporter for a while and he brings a lot of energy, [but] he doesn’t have any official role.”

Zimmerman also is affiliated with a complex web of pro-Paul Internet sites — some run out of his consulting offices — on which he suggests that he coordinates with Paul’s national committee.

“Don Zimmerman…responsibility for overseeing goals and outcomes of local group, liason [sic] with national campaign,” reads one post by Zimmerman in late May 2007 on RonPaulForums.com.

According to Web registration records, two other pro-Paul sites are registered to addresses also used by Zimmerman’s consulting businesses. RonPaulAustin.com, whose mission is to “promote the message and candidacy of Dr. Ron Paul,” is registered at 13492 Research Blvd. in Austin, the same address used by Zimmerman to receive Paul’s presidential fundraising checks.

Zimmerman, who registered the Web site under the name Ron Paul 2008 PCC, also has a consulting business registered to the same address. According to the site of another Web-based group, The Republican Liberty Caucus of Texas: The “Ron Paul” Republicans, the group’s political action committee was run out of the same Austin address.

As a contract fundraiser, one knowledgeable source said, Zimmerman’s access to resources and staff was analogous to other campaign employees: He could use whatever he needed to do his job, so long as he was being paid by the campaign. He also was quoted in June by the Austin American-Statesman as Paul’s Texas state coordinator, but the campaign denies he ever held that role.

Taken as isolated incidents, Zimmerman’s largesse is not unlike grass-roots political volunteers and Internet organizers coast-to-coast. Where he may have erred, however, is when he decided to register a political action committee that could be construed by federal regulators as a laundering operation for illegal or excessive campaign contributions.

“The fact that a person has an association with a [presidential campaign], by itself, isn’t sufficient to say everything they do [for the presidential campaign] is an in-kind contribution,” said Bob Biersack, a spokesman for the Federal Election Commission. “But sharing staff or leadership overlaps is one thing that can be considered.”

Biersack, who is barred from discussing ongoing investigations, said coordinated activity between campaigns is a particularly complex area of the law. Large issue-based PACs such as EMILY’s List employ teams of campaign finance lawyers that scrutinize employees and resources down to the last paper clip.

Since filing registration papers with the FEC last month, Zimmerman has learned firsthand just how frustrating the agency’s regulatory thicket can be. On Aug. 31, Zimmerman received a letter from FEC investigators asking whether he is affiliated with any other political committee. Given his past, some campaign finance experts claim, that may be a tough legal argument to construct. Adding insult to injury, Zimmerman has yet to raise any money for his political committee.

One fairly straightforward area of the law, Biersack said, involves advertising buys by political action committees and other groups. Coordinating between groups, without correctly accounting for the shared resources, is definitely a no-no and could bring FEC fines. Former FEC general counsel Larry Norton said the “issue really comes down to whether there is coordination between the two [organizations].”

“Do the people running [the ads] have access to information about spending needs” of the candidate’s committee, Norton said. “The person who has a principal role in [a political action committee] simultaneously has a role with the candidate’s committee, where they could be privy to information — what [television] markets do we simply not have the money for? What are the themes of our ads? — and then that person is in a position to be shaping the plans of a separate political action committee, that is a problem.”

Earlier this summer, The Boston Globe reported that a political action committee, Vote Hope 2008, set up a Web site to support the presidential campaign of Sen. Barack Obama (D-Ill.). Although Obama’s campaign denied any affiliation with the group, the group’s Web site implied that there was a connection. The group, started by high-profile liberal activists, said it wanted to seize on wealthy Democratic donors who already had maxed-out with $2,300 gifts to Obama. PACs can accept up to $5,000 from individuals.

Like Obama, Paul appears to be holding otherwise crucial activists like Zimmerman at an arm’s length. Benton, Paul’s spokesman, denied Zimmerman was fired by the campaign but said interactions between the campaign and motivated activists in the Internet age can become tense.

“Grass-roots supporters get frustrated because we can’t be as responsive as they’d like; they want guidance, they want to coordinate,” Benton said. “It’s something we need to keep focused on: How do we work with this grass-roots network, while staying within the confines of the law?”

Benton added: “It frustrates some of the grass-roots folks because we can’t work with them as they might wish.”