Carl Levin is retiring. (Melina Mara/Washington Post) Carl Levin is retiring. (Melina Mara/Washington Post)

Sen. Carl Levin (D-Mich.) will not seek reelection in 2014, he announced Thursday afternoon, saying he wanted to focus on the nation's challenges rather than politics.

In a statement, Levin explains that he and his wife "decided that I can best serve my state and nation by concentrating in the next two years on the challenging issues before us that I am in a position to help address; in other words, by doing my job without the distraction of campaigning for re-election."

The 78-year-old senator has held his seat since 1979; he is chairman of the powerful Armed Services Committee. He has not faced a close election in decades.

In his statement, Levin mentions corporate tax avoidance, the health of the manufacturing industry, campaign finance reform, military budget cuts, the end of the war in Afghanistan and veterans' care as issues he wants to address in his final two years in office.

A former civil rights lawyer, Levin was a leading critical voice on the war in Iraq. As chairman of the Senate Permanent Subcommittee on Investigations, he has investigated Enron, the credit card industry, the 2008 financial crisis, and offshore tax havens.

The senator is known as a hard-working advocate for his state, pushing to protect Great Lakes water and manufacturing jobs. A one-time line worker ad a Ford tractor factory, he pushed hard for the auto industry bailout.

Levin becomes the seventh senator to announce his retirement so far this year, including Sen. Jim DeMint (R-S.C.), who resigned in January.

The other retirees are Sens. Saxby Chambliss (R-Ga.), Frank Lautenberg (D-N.J.), Mike Johanns (R-Neb.), Tom Harkin (D-Iowa) and Jay Rockefeller (D-W.Va.).

Candidates who will likely look at the seat include Rep. Gary Peters (D-Mich.), but Democrats also must recruit for the governor's race against Gov. Rick Snyder (D-Mich.).

"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," Democratic Senatorial Campaign Committee Chairman Michael Bennet (Colo.) said in a statement.

On the GOP side, Attorney General Bill Schuette is one prospect, although he wrote on Facebook Thursday that he plans to spend six more years in his post. Rep. Justin Amash will also likely consider a bid. Republicans struggled to field a top-tier candidate against Sen. Debbie Stabenow (D-Mich.) last year, as former congressman Pete Hoekstra never seemed to recover from some early stumbles.

National Republican Senatorial Committee spokesman Brad Dayspring said the party has "been speaking to local officials and grassroots organizations in preparation for Senator Levin's potential retirement, and now that groundwork will start to pay off."