(CNN)Mississippi Republican Sen. Thad Cochran, who chairs the powerful Appropriations Committee, will leave his seat effective April 1, citing his health issues, meaning both US Senate seats in the state will be on the ballot this fall.
GOP Sen. Thad Cochran to step down April 1, both state's Senate seats on the ballot
"I regret my health has become an ongoing challenge," Cochran said in a statement. "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's announcement means Mississippi will now have two Senate seats up for grabs in November. It comes the week after conservative firebrand state Sen. Chris McDaniel -- who unsuccessfully challenged Cochran in a 2014 primary -- announced he'd take on Sen. Roger Wicker in this year's GOP primary.
Whoever wins the seat currently held by Cochran will finish out the term, which ends in 2020.
Following Cochran's announcement, McDaniel thanked him for his service and said all options are on the table regarding his political future and whether that would change, given the retirement announcement.
"I am currently focused on my campaign against Roger Wicker, but all options remain on the table as we determine the best way to ensure that Mississippi elects conservatives to the United States Senate," McDaniel said in a statement.
Republican Gov. Phil Bryant will appoint a replacement for Cochran to hold the seat until a November special election. A Mississippi Republican operative said an early list of names to watch as potential Bryant appointees includes state House Speaker Philip Gunn, Lt. Gov. Tate Reeves, secretary of state Delbert Hosemann, state auditor Stacey Pickering and agriculture commissioner Cindy Hyde-Smith.
A unique quirk that brings the potential for chaos in that special election: That special election will be a "jungle" race in which the candidates appear on the ballot with no party affiliation listed. If no one tops 50%, the top two finishers would advance to a runoff.
The Clarion Ledger reported that Bryant isn't interested in appointing himself to the seat, despite The Washington Post's report that Senate Majority Leader Mitch McConnell and President Donald Trump have urged him to do so in the event that Cochran stepped down.
The 80-year-old's health declined in the last few years and he is currently serving his seventh term in the Senate. He was absent from his duties in the Senate for a few weeks last fall with a urinary tract infection.
Longtime Senate aides, who observed Cochran regularly, noted privately that the senator seemed to have slowed down mentally in recent years but they acknowledge it's difficult to tell to what degree.
Cochran is the 10th longest-serving senator in history. In 1972, Cochran was elected into Congress and served until 1978, when he was elected into the Senate. He was the first Republican in more than 100 years to win a statewide election in Mississippi.
"I've done my best to make decisions in the best interests of our nation, and my beloved state," Cochran said in his statement Monday. "My top concern has always been my constituents in Mississippi. My hope is by making this announcement now, a smooth transition can be ensured so their voice will continue to be heard in Washington, D.C."