Ethics watchdog says Thune’s vote to confirm his son-in-law’s nomination was a conflict of interest

U.S. Senate Majority Leader John Thune, R-South Dakota, speaks to Rotary members on April 17, 2025, at the Elks Lodge in Watertown. (Makenzie Huber/South Dakota Searchlight)

A leader of a government watchdog group says U.S. Senate Majority Leader John Thune, R-South Dakota, had a conflict of interest when he voted to approve his son-in-law’s nomination to a federal job.

Thune voted yes Saturday on the confirmation of Luke Lindberg as undersecretary for trade and foreign agricultural affairs at the U.S. Department of Agriculture. Lindberg is married to one of Thune’s daughters, Brittany Thune Lindberg.

Donald Sherman, executive director and chief counsel at Citizens for Responsibility and Ethics in Washington, said U.S. Senate rules don’t overtly bar senators from voting on the confirmation of a family member. But the rules do bar members of Congress from using their office in a way that benefits family members.

“I don’t think you need to be an ethics expert to understand that there’s a conflict of interest here,” Sherman said. 

Thune’s immediate predecessor as Senate majority leader, Mitch McConnell, also a Republican, faced a similar situation in 2017 when his wife, Elaine Chao, was nominated to lead the Department of Transportation. After initially saying he would not recuse himself from Chao’s confirmation vote, McConnell ultimately voted “present.”

Sherman said Thune’s vote would not have made the difference on Lindberg’s nomination — the vote was 78-17 in favor — and there was no reason not to follow McConnell’s example. Sherman said Thune’s actions set a bad precedent.

“It emboldens other people to bend the rules for themselves,” Sherman said. 

Lindberg served as chief of staff and chief strategy officer at the Export‑Import Bank during the prior Trump administration, and later helped launch and lead South Dakota Trade, a public‑private partnership in the state aimed at expanding export opportunities for businesses.

U.S. Department of Agriculture Secretary Brooke Rollins praised Lindberg in a news release about his confirmation.

“We are thrilled to have Luke join our team and I have full faith that his drive and deep experience will ensure we not only defend our producers, but also open new doors to global trade,” Rollins said.

Thune’s office did not respond to multiple requests for comment.