There are, by my count, 13 Congressional districts outside of Arizona represented by a Democrat that voted for John McCain and where McCain did better in 2008 than George W. Bush did in 2004. In other words these are the districts that went in the wrong direction for Democrats even in a Democratic year and thus might really be hard to handle in what's looking like a not so Democratic year.
Probably not coincidentally 3 of the Democrats who have decided not to run for reelection so far came from those districts- Charlie Melancon in Louisiana and Bart Gordon and John Tanner in Tennessee.
It seems likely those folks saw the writing on the wall both from those hard election results and from their internal polling. We did a poll last month in the district of a 4th member of that group- Vic Snyder in Arkansas- and found him more or less tied with a bunch of guys who had no name recognition. I would not be surprised if it's a similar situation for some of the other folks on this list which includes:
-Jason Altmire and John Murtha of Pennsylvania
-Marion Berry and Mike Ross of Arkansas
-Nick Rahall of West Virginia
-Dan Boren of Oklahoma
-Lincoln Davis of Tennessee
-Allen Boyd of Florida
-Parker Griffith of Alabama
I'm pretty sure we'll go in and do a poll of either Rahall's district or Alan Mollohan's in West Virginia sometime next month to see what's going on there, and we may get around to looking at another of the Arkansas districts sometime soon as well. These may be hard holds for the Democrats even if the incumbents run again. If not prospects for holding them are really poor.