I want to know the answer to the following question:
The states defend their interests at the federal level through what?
All the background I'm provided with is that "According to the German constitution (called Grundgesetz or in English Basic Law), some topics, such as foreign affairs and defense, are the exclusive responsibility of the federation (i.e., the federal level), while others fall under the shared authority of the states and the federation; the states retain residual legislative authority for all other areas, including "culture", which in Germany includes not only topics such as financial promotion of arts and sciences, but also most forms of education and job training.". Is that enough to answer the question?
Answer: no