Via email, Alan Abramowitz sends a plot showing that President Obama's approval levels with various demographic and political groups in the January 17-23 Gallup poll are almost perfectly correlated with his 2008 vote share among those groups:

Abramowitz's finding is consistent with exit polls which showed that the swing against the Democrats in 2010 was relatively uniform across demographic groups. The implication is that politicians and the media spend too much time worrying about appeals targeting specific groups and too little on what moves support up and down across groups (principally, the economy).