WASHINGTON — Last month, Rand Paul greeted a crowd of like-minded supporters: gun-rights enthusiasts with a libertarian bent in New Hampshire, the state where the Republican senator seems most likely to chase presidential primary votes.

Event organizers wouldn't let press into the event, devoted to guns, but reporters were able to see Paul greeting supporters in a black letterman-style jacket bearing the letters "NAGR."

The acronym stands for National Association for Gun Rights — an alternative group to the behemoth National Rifle Association, the group that NAGR says just isn't committed enough to the Second Amendment.

Paul routinely signs his name to their mailers. He's helped fundraise for the group on conference calls. But NAGR is just one of the wide network of libertarian activist groups that Paul remains aligned with, even as he prepares for a presidential bid this year.

The informal network of groups — NAGR, the Campaign for Liberty, the National Pro-life Alliance, and the National League of Taxpayers — are something of a holdover from Paul's more libertarian purist father. The groups operate independently from one another and from Paul, but their connections to the family run deep. Their activists provided a foundation of operative support for Ron Paul's presidential campaigns. But they didn't stop when the elder Paul retired: The groups fundraise aggressively and many have used Rand Paul's name to solicit donations and raise their profile.

Voters on their massive distribution lists get communications with Paul's name or messages signed by him, gaining exposure and a fundraising base for him. An email from the National League of Taxpayers for example, will go out under Paul's name and ask supporters to sign a petition supporting a balanced budget amendment and then say contributions to the group are "urgently needed."

Rand Paul's connection to the network is no real secret — the libertarian groups were the subject of stories from reporters like David Weigel and others last year. The question in many of those stories was the same: If and when would the senator walk away from the groups.

A year later, the answer seems clear: Rand Paul isn't walking away from the groups, and they'll continue to use his name on their promotional materials, even if he can't control what they do.

The relationship between Paul's political operation and the groups is more fluid than brokered — many political operatives come up through organizing groups like these. Paul's top adviser, Doug Stafford, is himself a veteran of a libertarian-minded group, once serving as a top official at the National Right to Work Committee, including during the early days of his role as an adviser to Paul. Dudley Brown, NAGR's director, says he's known Stafford for years and supported the elder Paul's 2012 presidential bid. And Rand Paul has credited Campaign for Liberty director John Tate, who ran his father's 2012 presidential campaign, for playing a "crucial role" in bringing Stafford into his political orbit.

Stafford declined to comment for this story.

These days, Tate's group routinely sends out emails to its activist listserv with "pub notes" (a message at the top) signed by Paul — the latest hit inboxes on Feb. 10. He emphasizes the relationship on these fundraising appeals is not collaborative.

"We don't coordinate or work with Rand and never get calls from them saying don't do this, or please do this," Tate told BuzzFeed News.

Many people get the emails. But the mail is where the money is. A voter in Iowa might get mailers from all these groups — and many with Rand Paul's name on them. These groups really depend on the lucrative, effective method of direct-mail fundraising.

Public financial disclosures show that the groups invest heavily in their mail operations. NAGR, for example, spent more than $9 million combined on internet and mail communications in 2013, according to IRS filings from that year. The National Right to Work Committee spent close to $1.2 million on list rentals and $458,618 on mail that year, according to filings.

The emblematic figure in this direct-mail world is Mike Rothfeld, whose firm Saber Communications is a key part of Paul's PAC's digital operation. A YouTube video of Rothfeld from 2012 offers a glimpse of Rothfeld's philosophy — the operative downs cup after cup of coffee while explaining "the real nature of politics" to the Young Americans for Liberty National Convention.

"I figured out that if I could write words that would raise money, they'd pay me," Rothfeld says in the speech, of his early days in politics. "And I could, and I did. And then I figured out that if I could run political campaigns they'd pay me for that too, so I learned to run political campaigns. Rand Paul was a client, and is a client. And Ron Paul is a client."

"I am a professional junk mailer," Rothfeld goes on to say. "I am a professional telemarketer. I'm a professional spammer — like, a hundred million pieces of, emails a month. And I'm a professional negative campaigner. And I'm damn proud of all four." Rothfeld's influence in Paul world, despite some skepticism from the hardcore libertarians, is substantial. Rothfeld was formerly in charge of the National Right to Work Committee's direct mail operations in the late 1980s and early 1990s, and he is a board member of NAGR.

Rothfeld declined to comment for this story.

NAGR, the gun group, offers some lessons in how the relationship with the senator can work, and what benefits and perils exist.

The group believes in "constitutional carry," meaning every American citizen should be able to own guns without a permit and believes that firearm safety training should be optional.

Right before the 2014 midterms, Rand Paul and the NAGR hosted a call ostensibly about "Mike Bloomberg's $50 million war on guns."

Paul told the 6,000 or so supporters on the line that he was "proud to be associated with the National Association for Gun Rights" and its president, Dudley Brown. Brown in turn said Paul has done "an amazing job" standing for gun rights in the Senate.

Callers asked what it is they could do to help Paul and Brown.

"The only thing I'd say if each person on the phone call gave $100 you'd have $600,000," Paul said. "That's enough to make a difference in a close race."

Paul's connection to NAGR has caused some political tension in the past. The group presents itself as a more conservative alternative to the NRA — and runs ads against Republicans not sufficiently strong on gun rights, a frightening political prospect for many politicians, especially Republicans.

In 2012, NAGR's tactics pulled Paul into a public spat with a Republican congressman from Virginia, Scott Rigell, based on a number of ads the NAGR ran in his district that argued Rigell was trying to curb second amendment rights. (The ads also targeted former Majority Leader Eric Cantor, and in 2013, Sen. Susan Collins of Maine complained during a Senate GOP lunch that NAGR's ads were hurting her back home. Paul reportedly stormed out of the lunch.) Rigell confronted Paul, asking him to publicly refute the group or at least get them to stop attacking him. According to Rigell, Paul told him there was nothing he would do. At the time, Stafford told Politico, "Rand signs normal, run-of-the-mill activist emails and letters for numerous groups and this is one of them. That's all he's ever done for them, he's not affiliated with the group in any way, he doesn't control how they decide their activism should take place in terms of who the people are that need to be shored up on an issue."

Two years later, Rigell is still furious with Paul over the ads.

"He was completely indifferent to the truth. It speaks to his character and he's a man and public figure lacking in character. I think he is unworthy of the office he holds but certainly of a higher office," Rigell told BuzzFeed News.

"This will over time become increasingly an issue," Rigell added. "Not just because of what happened to me personally but because of the pattern that is there of working with groups that use nefarious methods and outright deception… And when presented with it, as a fellow member of congress and a fellow Republican, he was indifferent to it."

Asked about Rigell's comments, Paul's office declined to comment.

Rigell is not especially well known and the episode did not damage Paul broadly — but it offers a window into how an uncoordinated, though associated group could create public problems in a presidential cycle.

Brown, the president of NAGR, downplayed the connections his group and others have to Paul's political operation, citing the natural overlap of people within a political movement. (Though he did note that, when it comes to 2016, he didn't "see anybody on the horizon who is as strong on the gun issue as Sen. Paul is.")

"When I see, 'Oh wow, there all these connections,' all you have to do is spend 10 minutes on Facebook and LinkedIn and this and that and almost every single person in a real political movement in Washington, D.C., has a thousand connections," Brown said.

"I've been personal allies with a lot of people in the conservative movement," he said.

The tension between what might be good for Paul politically and what might be good for a group with a clear, narrow policy agenda is something that Tate is aware of, but said it wasn't an issue for the Campaign for Liberty. He said the group does not coordinate on fundraising with Paul, and while they do on some policy issues, he argued they don't pull punches.

"We work with Rand's office legislatively, for example on audit the fed," Tate said. "There's not any kind of coordination or effort to only do things that will help him or only do things that won't hurt him."

Tate stressed that the Campaign for Liberty emails that go out under Paul's name — which arrive in inboxes from a "rand.paul@campaignforliberty.com" email address — only include Paul as part of the "pub note," or introduction to the main body of the email.

"We never have him or any member of congress sign the actual email itself," Tate said. "It's more of a, 'hey, take a look at this.' We propose copy over and they send it back with yes or no." The group commands a large email list — a few million strong, Tate said.

He acknowledged that the Campaign for Liberty's deep ties to the Paul family can make it at least look like there is some kind of coordination going on for the Pauls' electoral benefit, but dismissed the idea.

"We've been through this once with Ron, and I guess my short answer is yes, it's always in the back of my mind and a concern, but we've already been through it," Tate said.

"A good friend of mine who's an attorney said no organization in America can follow to the letter the FEC, the IRS, the postal regulations, and state and local law, because in many cases they conflict with each other. Because of those, not fears, but concerns, we make sure that whatever the line is on activities by 501c4s, we step back five paces," he said. "There are people who assume we were only founded to help Ron run for president or help Rand run for president. Most people have realized that's not why we exist."

Paul's emails to Campaign for Liberty don't always have to do with legislative priorities for the group. The most recent, for example, exhorts activists to attend a "Political Leadership School" session run by the Delaware branch of the organization, because "you really do owe it to your ideas and principles to learn how to become the most effective activist you can be."

The groups, and wider world of the libertarian movement, became a more acute issue during the 2012 campaign, when a top aide was accused of bribing an Iowa state senator to switch his endorsement from former Rep. Michele Bachmann to Ron Paul.

The scandal originated with Aaron Dorr, an official from Iowa Gun Owners, a state-based group that has worked closely with NAGR and Brown (the two held a rally together as recently as October of 2014 prior to the midterm elections in Iowa).

In an October 2011 email, Dorr wrote that the state senator, Kent Sorenson, needed to be put on the payroll in exchange for endorsing Paul and giving the campaign a list of homeschoolers for targeted mail. The memo was sent to Tate. A former Paul campaign official, Dennis Fusaro, leaked this and other materials implicating the Paul campaign in the Sorenson bribe.

Last year, Sorenson pleaded guilty to illegally concealing campaign money — and admitted to taking $73,000 from Ron Paul's presidential campaign in exchange for an endorsement. No one else has been charged for any kind of crime related to the episode.

At the time, though, Jesse Benton, a longtime political operative for Rand Paul who is also married to the senator's niece, resigned from Mitch McConnell's re-election campaign, on which he was serving as campaign manager.

The crisis seems to have passed. Benton has since launched a new firm, and Rand Paul has said that he'll be a part of the 2016 operation.

Fusaro, now gone from the Paul political orbit after the leak, remains a critic of the way the way the libertarian groups function, and specifically the connection between the groups and direct mail. But in a phone call with BuzzFeed News last summer, even he acknowledged the big upside.

"The direct mail program and the other means they use to mobilize grassroots people on specific issues are building an army for Rand Paul," Fusaro said. "That's what they're doing. It's good politics, in one sense."