Former Kansas Secretary of State Kris Kobach is using a nonprofit group he advises to raise money for his U.S. Senate campaign, and legal experts say one recent fundraising push likely ran afoul of federal campaign finance laws.

On Thursday, Kobach sent a fundraising appeal to an email list maintained by We Build The Wall, a 501(c)(4) advocacy group currently attempting to build a wall on the southern border using private funds. Kobach is on the group’s advisory board and serves as its general counsel.

“As a donor to WeBuildTheWall, I humbly ask you to support my run for the Senate,” Kobach’s email pleaded. The email provided links to the campaign’s official fundraising page and asked for “a financial contribution of $50, $100, $250, $500, or any amount up to the maximum of $2,800 per individual.”

The solicitation likely violated federal campaign finance laws, according to Paul S. Ryan, the vice president for policy and litigation at the group Common Cause.

“At a minimum, this Kobach for Senate fundraising solicitation email appears to violate the ‘paid for by’ disclaimer requirement” for official campaign communications, Ryan said in an email, referencing the requirement that campaigns clearly disclose the financial sponsors—generally the campaigns themselves—behind official political communications.

Kobach’s email might be above board if his campaign paid fair market value for its use of the We Build The Wall list. But in that case it would be legally required to include that “paid for by” disclaimer, which was entirely absent from the Thursday email. That makes it unclear whether the Kobach campaign was actually behind the email, or whether Kobach himself sent it in his capacity with—and using the resources of—We Build The Wall, which would raise a host of other legal problems.

“If the Kobach committee did not pay fair market value for the cost of disseminating this email,” Ryan explained, “then the Kobach committee has arguably committed the more serious campaign finance law violation of receiving a corporate contribution in the form of a coordinated expenditure.”

Even if We Build The Wall sent the fundraising email independently of Kobach or his campaign, and without their knowledge or consent, that would likely raise a host of other issues. It might amount, for instance, to an in-kind contribution to Kobach’s campaign, and as an incorporated entity, We Build The Wall can’t directly donate to federal political campaigns, in-kind or otherwise.

Neither the Kobach campaign nor We Build The Wall immediately responded to inquiries about the email and whether the campaign paid for use of the group’s list.

Kobach officially entered the Kansas Senate race last month, and has said he would continue serving as We Build The Wall’s general counsel during the campaign. He is one of five Republicans seeking the nomination to replace retiring Sen. Pat Roberts. In 2018, Kobach lost the Kansas gubernatorial race to Democratic Gov. Laura Kelly.

His role at We Build The Wall began in the wake of the Trump administration being stymied by Congress for its demands that it pass legislation funding the construction of a wall on the southern border. The organization was criticized for its opaqueness around both its funding sources and mission as well as the controversial background of its founder. But Kobach’s position there has drawn additional scrutiny as his candidacy for the Senate receives promotion through official channels at the nonprofit.

At an event held by the group in New Mexico last week, former Rep. Tom Tancredo, another We Build The Wall advisory board member, urged attendees to support Kobach’s candidacy. “That does not establish any connection between the two organizations,” a Kobach spokesperson told the Wichita Eagle of Tancredo’s comments.

Thursday’s fundraising email does appear to establish such a connection.

“You’ll sometimes see a campaign paying to rent a c4’s list, but that’s clearly not what’s happening here,” said Brendan Fischer, the director of federal reforms at the Campaign Legal Center. “[T]he content of the message describing a We Build the Wall event and the logo at top make clear it is an official communication from the c4 itself.”

In the email, Kobach even compares his role as the nonprofit’s top lawyer to the one he hopes to play in the upper chamber of America’s legislature, writing, “I'm [sic] want to represent you in the United States States [sic] the same way I'm going to continue to represent WeBuildTheWall as General Counsel.”