Carl Levin (D-MI) speaks at a September 11, 2007.National Journal

This article is from the archive of our partner National Journal

Sen. Carl Levin of Michigan announced late Thursday that he will not seek a seventh term in 2014, leaving Democrats with another open seat to defend next year.

Levin called the decision "extremely difficult" and said he wanted to focus on his role as chairman of the Senate Armed Services Committee "without the distraction of campaigning for reelection."

Levin is the fourth Democratic senator to announce he won't run for reelection — Sens. Tom Harkin of Iowa, Frank Lautenberg of New Jersey, and Jay Rockefeller of West Virginia have all announced this will be their last term, and South Dakota's Tim Johnson is considered likely to join them. With the exception of Lautenberg, their departures create a problem for Democrats as they try to retain their majority in the chamber. Had Levin chosen to run, he would have been a heavy favorite, but now Republicans may smell a pickup opportunity.

Michigan Democrats have been readying for a challenge to Gov. Rick Snyder, but they'll now face the added burden of retaining the Senate seat. They've had success in that area, holding both  seats in the upper chamber for more than a decade. "We win on the federal level,"  newly installed Michigan Democratic Party Chairman Lon Johnson said in a phone interview Wednesday, before Levin's announcement.

"Our challenge," said Johnson, "is to convert those victories to the state level."

The challenge now will be mounting campaigns in two heavily contested statewide races — with the possibility that one race could thin the candidate pool of the other.

Colorado Sen. Michael Bennet, chairman of the Democratic Senatorial Campaign Committee, expressed confidence the seat would stay in Democratic hands. "I am confident that we will recruit a great Democratic leader who will continue to fight for the values and priorities Senator Levin advocated for all these years," Bennet said in a statement. "We fully expect to keep Michigan blue in November 2014."

Potential Democratic candidates include Rep. Gary Peters and former Rep. Mark Schauer.

In a statement issued from his House office, Peters said Levin "belongs alongside Michigan's greatest statesmen," but he did not comment on a potential run for his seat. "When I began my own career in public service, his was the example I held myself up to," said Peters. "Like Carl has for so many others, he became a mentor to me over the years and I'm proud to call him my friend."

Former Gov. Jennifer Granholm has also been mentioned as a potential Democratic candidate.

On the GOP side, Attorney General Bill Schuette, who lost to Levin in 1990, is considered a strong possibility, and state Sen. Roger Kahn has expressed interest. A Republican official suggested Michigan Secretary of State Ruth Johnson, Lt. Gov. Brian Calley, and Rep. Mike Rogers might also be interested in running. Rep. Justin Amash was also reported to be interested in a bid if Levin retired.

While the candidate field remains unclear, the GOP is in a stronger position with Levin off the ballot, both in Michigan and in its quest to retake the Senate. Republicans have defeated only three Democratic Senate incumbents since 2004: Tom Daschle of South Dakota in 2004, and Russ Feingold of Wisconsin and Blanche Lincoln of Arkansas in 2010. Even with a favorable Senate map in 2014 — Democrats hold seven seats in red states up for reelection — winning the net of six of them necessary for a majority was a tall order against a slate of incumbents.

But these retirements offer a way around that. Republicans could hypothetically knock off only two incumbents and still gain control of the upper chamber. "Over the last few months, the 2014 map has gone from sorta difficult to really tough for Senate Democrats," said Brad Dayspring, National Republican Senatorial Committee spokesman.

This article is from the archive of our partner National Journal.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.