Mississippi Sen. Thad Cochran, a former chairman of the Senate Agriculture Committee and the current chairman of Appropriations, says he will retire April 1, citing health reasons. 

His resignation will set up a special election for his seat. 

Cochran, 80, was the first Republican to win a statewide election in Mississippi in more than 100 years when he first won his Senate seat in 1978. He retires as the 10th-longest serving senator in history.

“I regret my health has become an ongoing challenge. I intend to fulfill my responsibilities and commitments to the people of Mississippi and the Senate through the completion of the 2018 appropriations cycle, after which I will formally retire from the U.S. Senate," Cochran said in a statement.

The Appropriations Committee is finishing work on a fiscal 2018 omnibus spending bill that Congress needs to pass by March 23, when a stopgap spending measure expires. 

Cochran worked his way up in seniority on the Agriculture Committee, where he had a keen interest in cotton policy and nutrition programs, and served as chairman from 2003 to 2005. 

Later, he would assert his seniority and take over as ranking member of the committee in 2013 to work with then-Chairman Debbie Stabenow, D-Mich., to craft what became the 2014 farm bill. In 2015, with Republicans back in control of the Senate, Cochran took over the chairmanship of Appropriations and Pat Roberts, R-Kan., became chairman of Agriculture. 

Cochran and his staff recently played a key role in using a budget bill to make seed cotton eligible for the Price Loss Coverage program. 

“His insight on the challenges facing agriculture and his leadership in shepherding important farm policy through the Senate are greatly appreciated by the U.S. cotton industry," said Ron Craft, a Texas cotton ginner who is chairman of the National Cotton Council. Cochran "has been a tireless advocate for providing adequate funding for the cotton industry’s priorities and programs."

Cochran served three terms in the House after first winning election in 1972.