If Obama's approval rating is 45 percent the GOP would pickup 15-20 seats. If it is 50 percent they gain about 10 seats.
For the GOP to take back the House, Obama would have to be at 35 percent or below; it's hard to find 40 seats that are even realistically winnable, much less going out and actually winning them.
Basically, if the Republicans take back the House, they will probably win the presidency in the following year. Sure, you will talk about Bob Dole and Mike Dukakis...but I will simply respond with Barack Obama and Dwight Eisenhower.
To use the Barack Obama and Eisenhower examples, the party needs Eisenhowers or Obamas rather than Dukakis's and Doles. Right now the field(Romney, Palin Pawlenty) looks a lot more like Dukakis than it doe either of the winners.
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