Hawaii’s U.S. Senator Daniel K. Akaka will not run for reelection in 2012.

Akaka’s retirement brings to 12 the number of members of the 112th Congress — 5 Senate and 2 House Democrats and 2 Senate and 3 House Republicans that have announced plans to leave Congress on or before the January 3, 2013 end of the 112th Congress:

SENATE

Democrats

1. Daniel Akaka (HI) Retiring
2. Jeff Bingaman (NM) Retiring
3. Kent Conrad (ND) Retiring
4. Joe Lieberman (Independent Democrat – CT) Retiring
5. Jim Webb (VA) Retiring

Republicans

1. Kay Bailey Hutchison (TX) Retiring
2. Jon Kyl (AZ) Retiring

HOUSE

Democrats

1. Jane Harman (CA) Resigning
2. Christopher Murphy (CT) Running for Senate

Republicans

1. Jeff Flake (AZ) Running for Senate
2. Chris Lee (NY) Resigned
3. Denny Rehberg (MT) Running for Senate

Democrats must defend 21 of the 33 Senate seats in up for election in 2012. Counting the two so-called Independents who caucus with the Democrats, Akaka’s departure means five of those seats will be up for grabs without a Democrat incumbent.

The Democrats’ 53-47 Senate majority is looking more and more precarious.

From Right Side Politics’ 112th Congress critter departure watch.