Congressional Republicans seem to want to run on local issues this fall. The White House thinks it can win with a national campaign. At the moment, I think the former is a counsel of despair, and that the latter depends upon the Democrats continuing to be Democrats. If the Democrats were credible on national security (theyre not yet, and havent been in quite some time) and moderate on some cultural issues, the Republicans would be staring minority status in the face.
If you favor "structural" explanations of recent Republican electoral successes, youll like this.