A candidate in the North Carolina U.S. Senate race is getting some help from an unlikely source: A conservative group with past ties to the right-wing billionaire Koch brothers.

In what appears to be an effort to siphon votes from the Democratic incumbent, an organization called the American Future Fund (AFF) has spent almost a quarter of a million dollars on an ad campaign to promote a third-party candidate – Libertarian Sean Haugh – with the slogan “More weed, less war.”

The goal is to get younger voters to cast ballots in favor of Haugh instead of Democrat Kay Hagan, who is trying to fight off Republican challenger Thom Tillis. Haugh is running on a pro-marijuana platform, while Hagan is opposed to marijuana legalization and Tillis has not taken a stand on the issue.

During the 2012 election cycle, two organizations backed financially by Charles and David Koch reportedly contributed 92% of AFF’s funding.

One of those organizations – Freedom Partners – said it isn’t funding AFF now and had nothing to do with the ad campaign. AFF, however, isn’t required to disclose its donors, so where it gets the money for the Haugh ad campaign may never come to light.