Are Americans Stupid?

Since we are currently researching our candidates for the NJ 12th District House of Rep, I decided to provoke a question on more local terms.

With the congress's approval rating getting lower and lower, I ask you why do we continue to elect the same people for congress and senate?

It seems to me that they are not representing us as we wish, if we do not approve of our actions, but come election time, it is still a walk in the park for the incumbents.