I guess the bad economic news is turning some away from the incumbent party:

RCP Average        09/09 - 09/21        --        48.1        45.4        Obama +2.7
CNN/Opinion Research        09/19 - 09/21        697 LV        51        47        Obama +4
Gallup Tracking        09/19 - 09/21        2740 RV        48        44        Obama +4
Rasmussen Tracking        09/19 - 09/21        3000 LV        48        47        Obama +1
Hotline/FD Tracking        09/19 - 09/21        922 RV        47        42        Obama +5
Battleground Tracking        09/14 - 09/21        800 LV        47        48        McCain +1
CBS News/NY Times        09/12 - 09/16        LV        49        44        Obama +5
Quinnipiac        09/11 - 09/16        987 LV        49        45        Obama +4
Pew Research        09/09 - 09/14        2307 LV        46        46        Tie