Kevin Drum doesn't believe that the election is referendum on Obama:
[T]he backlash against Obama probably isn't all that strong to begin with. As I mentioned on Friday, basic structural factors suggest a Democratic loss of 45 seats in the House this year. If Democrats instead lose 55, that's evidence of a backlash, but not actually a very big one. It means that we're still fundamentally the 50-50 nation we all talked about so much after the 2000 election, and a small shift among a small number of voters makes a big difference. It's true that voters are frustrated and tired, but I think it's a mistake to allow TV shoutfests to exaggerate just how frustrated and tired they really are.
Chart above via John Sides.