Republican Senator Thad Cochran (R-MS), 80, chairman of the powerful Appropriations Committee, said on Monday he will resign on April 1 because his "health has become an ongoing challenge."

"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.   

Cochran is the chairman of the Appropriations Committee. His announcement comes as Congress aims to pass a mammoth government funding bill by March 23, and after months of speculation about his health.

Cochran was first elected to the Senate in 1978 and currently serves as the chairman of the Senate Appropriations Committee.

As the Daily Beast notes, the decision puts the spotlight on Chris McDaniel, a conservative Republican who is trying to unseat Mississippi’s other senator, Roger Wicker.