Who wants to leave the U.S. House?

It's that time again.

Party officials, political observers and prospective candidates have begun the biennial guessing game about which House members will choose to retire. And even before the talk and speculation really ramp up ahead of filing dates for the 2012 primaries, some lawmakers are way ahead of the discussion, having already indicated they plan to say goodbye to Capitol Hill.

Just last month, two House members announced they will not be candidates for re-election in 2012: Dan Boren (D-Okla.) and Lynn Woolsey (D-Calif.).

Now, as a primer for the full exodus to come, we review where to look for the next slew of House retirements and what's prompting the lawmakers to leave:

• Redistricting and competition: Ahead of the 2012 election, many states are poised to undergo a potentially significant redistricting of their congressional jurisdictions designed to reflect updated population numbers from the 2010 census. But those remaps could place sitting incumbents in districts filled with voters they've never before represented--or, in some cases, force a loss of their district altogether. This latter scenario could mean that some members could find themselves running against a House colleague just to keep a spot in Congress. Many states are significantly retooling their district maps, but California, Georgia, Illinois, Iowa, Michigan and North Carolina are likely to pose the greatest peril to sitting members. (One big caveat here is that for nearly all of these states, the new maps are not yet finalized.)

Among the members who are rumored to be considering a district-based retirement plan: Democrats Lois Capps, Jim Costa and Laura Richardson and Republicans Dan Lungren, Ken Calvert, Elton Gallegly (who attempted to retire in 2006), and Buck McKeon; North Carolina Democrats Brad Miller, Larry Kissell and Heath Shuler (who also has a potential job prospect on the horizon-- see below); and Illinois Republicans Judy Biggert, Bobby Schilling, Joe Walsh and Don Manzullo.

Party observers will be closely watching all competitive House races, including those involving redistricting changes, for sitting incumbents who would rather bow out of Congress than fight a difficult battle in 2012.

• Age and health: As each session passes, observers attempt to guess when Congress' oldest members will call it quits. Many of these lawmakers have stated no intention whatsoever of retiring--while others (even those who are not considerably older than their colleagues) have revealed health issues that have set off speculation about their future plans.

Older members frequently the subject of retirement rumors include: Texas Republican Ralph Hall, 88-- currently the oldest member of Congress; Michigan Democrat John Dingell, who turns 85 tomorrow and is the longest-serving current member of Congress; New York Democrat Charlie Rangel, 81, who was censured in December for a litany of ethics violations last year; Florida Republican Bill Young, 80; Alaska Republican Don Young, 78; and California Republican Jerry Lewis, 76.

Meanwhile, the following lawmakers are facing health issues that have landed them some retirement watch lists, though none have indicated plans to retire: Arizona Democrat Gabrielle Giffords continues to recover from being shot in the head during an attack at a town hall event in January. Georgia Democrat John Barrow recently disclosed he is undergoing treatment for prostate cancer while his district also faces a potential redistricting drama. New York Democrat Maurice Hinchey is being treated for colon cancer and his state will emerge from the redistricting process with a loss of seats. And New York Republican Richard Hanna underwent heart surgery this past February.

• Job prospects: For one group of lawmakers, the House is is no longer enough. Nine House members have already announced plans to run for Senate, two are running for governor in their home state and one, California Democrat Bob Filner, is running for local mayor. In some cases, such as the Senate campaign of Indiana Democratic Rep. Joe Donnelly, the candidate faced a choice between a potentially dicey redistricting remap or moving up the ranks. Some House members are still weighing runs for other political offices, while others are weighing entry into the private sector.

Among the members potentially eying new jobs: Utah Republican Jason Chaffetz is likely to jump into his home state's Senate race, while his Democratic House colleague Jim Matheson is reportedly being recruited for that same race or his state's governor's election at the same time he faces potential redistricting headaches. North Carolina Democrat Heath Shuler is reportedly considering a job as athletic director at the University of Tennessee where he was a star quarterback. Massachusetts Democrats Ed Markey and Mike Capuano are both being assessed as potential Senate candidates. Minnesota Michele Bachmann has "suspended" her congressional bid as she pursues a presidential run, while Michigan Republican Thad McCotter won't confirm whether he'll run for re-election to the House now that he's running for president.