Everyone else is forgetting two things that Bush seems to remember.
1. Whether his approval rating is 10% or 90% he is still the President, with the powers that go with the job.
2. He is not running for office in November. The only way for his approval rating to affect the outcome is if the candidates actually running panic and forget that.
In other words, BFD. This could be turned around in a week with something like Congressional Hearings on protecting terrorists from military surveillance.
So, chill.
I think you are forgetting something as well...
1. Powers are useless when he refuses to enforce the law
2. No, but the GOP is, and his ratings will matter come the primaries, as they will be associated with the party as a whole