http://www.sos.state.ia.us/elections/voterreg/regstat.htmlActive voter registration as of 03/02/2007
CD 1: Dem 117,937 (31.9%) / Rep: 97,141 (26.2%) / NP 155,010 (41.9%)
[2006 Dem 55% / Rep 43% / Others 2% * open seat prev. Jim Nusle (Rep)]
CD 2: 138,897 (36.2%) / Rep 98,753 (25.7%) / NP 146,574 (38.1%)
[2006 Dem 51% / Rep 49% * Democratic pick-up prev. Jim Leach - the most liberal House Republican]
CD 3: Dem 139,645 (35.3%) / Rep: 119,434 (30.%) / NP 136,784 (34.6%)
[2006 Dem 52% / Rep 46% / Others 2% - Democratic hold Leonard Boswell]
CD 4: Dem 113,945 (29.2%) / Rep 119,674 (30.6%) / NP 157,102 (40.2%)
[2006 Rep 57% / Dem 43% - Republican hold Tom Latham]
CD 5: Dem 90,107 (24.6%) / Rep 144,595 (39.5%) / NP 131,710 (35.9%)
[2006 Rep 58% / Dem 36% / Others 6% - Republican hold Steve King]
Total: Dem 600,531 (31.5%) / Rep 579,597 (30.4%) / NP 727,180 (38.1%)
According to the CNN 2004 exit poll: 36% identified as Republican; 34% Democrat and 30% Independent
Bush, basically, won because he lead Kerry 55% to 43% among Independents. Democrats and Republicans were more or less equally loyal to their party's nominee
It clearly moved towards the Democrats in the 2006 mid-terms. In CD2, even a long serving and popular liberal Republican couldn't be saved. Not many tipped Leach to lose. If nothing changes issue wise, I'd say it favors the Democrats in 2008 but much will depend on who the nominees are and who appeals most to Independents. It will likely be close
I don't know whether a particular demographic trend is in effect, which might tilt the balance on in the favor of one party or another, however
Dave