The logo of the National Rifle Association is seen at an outdoor sports trade show on February 10, 2017 in Harrisburg, Pennsylvania. [DOMINICK REUTER/AFP/Getty Images]

Another campaign watchdog has filed a complaint with the Federal Election Commission accusing the National Rifle Association of illegally coordinating its support for three GOP Senate candidates.

The latest complaint, from the American Democracy Legal Fund — the legal arm of the liberal super PAC American Bridge 21st Century — says the NRA “made illegal in-kind donations to the Senate campaigns of Richard Burr, Matt Rosendale, and Josh Hawley in the form of coordinated television advertisements” and calls on the FEC to sanction the group. It is the fifth complaint to be filed with the FEC demanding an investigation into the NRA’s use of the same vendors as the campaigns it supports to evade laws barring campaigns from sharing information with outside groups.

Like the previous complaints, from the nonpartisan watchdog Campaign Legal Center and the Giffords Law Center to Prevent Gun Violence, the ADLF complaint relies on reporting by The Trace, which has teamed up with Mother Jones to investigate the NRA’s finances and political influence.

Earlier this month, The Trace and Mother Jones reported that both the NRA and the campaigns of Burr, Rosendale, and Hawley used a firm called National Media Research, Planning, and Placement or its affiliates to purchase television advertising. In several cases, Federal Communications Commission records show, National Media’s chief financial officer, Jon Ferrell, authorized ad purchases for the campaigns and the gun group at the same time. While election laws permit campaigns and the outside groups that support them to use common vendors, FEC regulations require the vendors to establish internal “firewall” agreements to ensure that the firm doesn’t act as a conduit for information.

Paul Shumaker, a consultant for the Burr campaign, told The Trace that National Media said it had such a firewall in place. “The Burr Campaign was informed by [National Media co-founder and CEO] Robin Roberts that they had all internal agreements in place,” he said. “The Burr campaign is fully prepared to respond to the FEC when they receive the complaint.”

Asked how such a firewall agreement would permit Ferrell to buy ads for both the NRA and Burr, Shumaker said, “You need to be talking to National Media.”

National Media, the NRA, and the offices of Burr, Hawley, and Rosendale did not respond to requests for comment.

Jessica Furst Simpson, an attorney for Hawley’s campaign consultancy, OnMessage, told The Raleigh News & Observer that the complaint was “a partisan press release.”

“The Hawley campaign and its vendors take compliance very seriously, and maintained and executed comprehensive, compliant firewalls upon advice of counsel,” she told the paper. “Suggesting otherwise is nothing shy of an attempt to manipulate the legal process and the press for political gain.”

The Campaign Legal Center has alleged in an FEC complaint that OnMessage itself was a conduit for illegal coordination between the NRA and a variety of GOP Senate candidates in 2014 and 2016, through a “functionally indistinguishable” shell company called Starboard Strategic.

Simpson did not respond to a request for comment from The Trace.