In a statement, Cochran said he intends to complete the appropriations cycle before retiring. "I've done my best to make decisions in the best interests of our nation, and my beloved state", Cochran said in announcing his decision to step aside.
"My top concern has always been my constituents in MS", he continued.
Cochran hasn't been as visible on Capitol Hill in recent months. He has served as Appropriations chairman of the Senate since his re-election in 2014.
Governor Phil Bryant will now begin the process of appointing a replacement for Senator Cochran.
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.
Cochran, was born in Pontotoc and lived in Tippah County where his parents were teachers at Blue Mountain College before his family moved to central Mississippi.
Espy became Assistant State Attorney General from 1984 to 1985, when he was elected as a Democrat to the 100th Congress in 1986 from Mississippi's 2nd congressional district.
A mild-mannered Southerner, Cochran played an insider's game throughout his seven terms - particularly as a member of the powerful Appropriations panel, which had always been a bipartisan powerhouse and way to funnel taxpayer dollars back home. Cochran, who is 80, has been suffering from health problems recently. In the runoff, with the help of crossover Democratic and African-American voters, Cochran prevailed.
Whoever wins the special election in 2018 would have to run again in 2020 - if he or she chooses. Already, state Rep. David Baria, the state House Minority Leader, has launched a Senate bid to challenge Wicker. "It'll be exciting to see who is actually going to be appointed to that position".
The Latest on the retirement of Mississippi Sen. McDaniel said he had no connection to the incident.
It's not clear yet who will replace Cochran.
"I just learned of the pending resignation of Sen".
This will be McDaniel's first appearance in Wicker's backyard since announcing his candidacy last week. Chris Van Hollen of Maryland, said his party will have "good candidates" in both Senate races in Mississippi.
When asked about a possible appointment, Meg Annison, a spokeswoman for Gunn, praised Cochran and said the speaker "was focused" on the ongoing 2018 state legislative session. But that takes time, money and hard work.