Senator Carl Levin, D-Mich, says he will not seek re-election in 2014.
The democratic senator says he wants to do his job as Senate Armed Services chairman and as an advocate for his home state "without the distraction of campaigning for re-election."
Levin was first elected to the Senate in 1978 and is the longest-serving senator in Michigan's history. The 78-year-old lawmaker called the decision was "extremely difficult." He says he loves representing the people of Michigan and fighting for what he believes is important for them.
"As Barbara and I struggled with the question of whether I should run again, we focused on our belief that our country is at a crossroads that will determine our economic health and security for decades to come," Levin said.
"I can think of no better way to spend the next two years than to devote all of my energy and attention to taking on these challenges," Levin said.
Levin's retirement opens a seat for Democrats in a state where Republicans have fared well in recent state elections. democrats have to defend open seats in West Virginia, Iowa and New Jersey in the aftermath of three retirements.