Updated at 3:26 p.m.

Democratic Rep. Dan Boren announced Tuesday that he won’t seek another term, becoming the first House incumbent this year to retire without running for higher office.

Speaking in his hometown of Muskogee, Okla., the 37-year-old Blue Dog Democrat cited the campaign fatigue for his decision to retire.

“This is not an easy decision for me,” he said in a statement. “It was based on the demands of constant campaigning, and most importantly spending too much time away from my family, which includes two very young children.”

Already, Boren’s predecessor, former Democratic Rep. Brad Carson, has reportedly announced plans to run for the seat. Carson vacated the seat to run for the Senate in 2004.

Boren’s retirement is particularly troubling for Democrats, as he leaves behind an Oklahoma seat that Republicans will be favored to win. As one of few Democrats to survive in a conservative district in 2010, the son of former Sen. David Boren (D-Okla.) seemed to have a lock on a district that voted nearly two-to-one for Arizona Sen. John McCain (R) in the 2008 presidential race.

More than other states, Oklahoma swung against the Democrats in the 2008 presidential election and then in the 2010 governor’s race, when Republicans swept every major race except Boren’s.

Through it all, though, Boren continued to win, including with a healthy 57 percent of the vote last November, even as so many other well-liked conservative Democrats fell victim to their national party’s agenda in Washington.

It’s far too early to say whether his retirement will be part of any kind of trend. In fact, the retirement picture is notable for it’s complete lack of trends; Boren is the first incumbent who isn’t running for Senate to head out the door. (So far, five House incumbents in each party are running for Senate.)

This comes in contrast to the Senate, where there have already been six retirements on the Democratic side and the party faces a tougher 2012 because of it.

While there is a premium on senators making up their minds early, the House retirement picture tends to come into focus much later. That goes double this cycle, when members are waiting to see how their districts are redrawn in the decennial redistricting process.

Though the GOP-controlled redistricting process is already finished in Oklahoma, Republicans spared Boren major changes and effectively gave him a very similar district to the one he has now.

Boren’s seat becomes the second open Democratic seat that Republicans will be favored to win — the other being the seat that Rep. Joe Donnelly (D-Ind.) was effectively redistricted out of (Donnelly decided to run for Senate rather than in the new district). The GOP also has a chance to win seats being vacated by Senate candidates Chris Murphy (Conn.) and Martin Heinrich (N.M.).

Republican retirees are largely leaving behind conservative districts.