You realise you can argue the exact opposite too, right?
Batman Begins - Came out during Bush administration
Gotham's economy is suffering and the people of the city are tired. Batman tackles corruption, takes down selfish, backstabbing board-memebers, he takes the power back from those in charge and delivers it to the people.
The Dark Knight - Obama "Rises"
All about Dent's change, betting it all on one figure to battle the corruption by legal means. The whole idea of putting trust in the people, and letting people make decisions themselves (the ferry scene). This film is the transition between a Gotham controlled by corrupt bureaucrats and under-the-table deals, to a Gotham for the people, by the people.
The Dark Knight Rises - Defending the current order of things
It's been peace time for years, and now an opposing force comes in, guns a-blazing (similar to how many conservatives have threatened to "take back the country with force"), threatening to take that all away. They smear Dent's name by throwing the Two-Face fiasco in the peoples' faces and instead of remembering the good Dent did, they are starting to focus on the bad.
The great thing about these films is the duality of the political undertones. They're not just one side of the political spectrum; it's both and even then it points out the faults in the actual system overall.