Local and State politics primarily, in my opinion. Studies "consistantly" show that if a school is provided properly trained and paid teachers, who work in an environment and with the necessary equipment and materials conducive to learning, most students will learn and learn well.
States and local politicians have well within their power to make sure this is the case; and they don't! They choose to use their resources in other ways and to make things worse for schools while blaming the federal government for problems they caused. In my opinion, they are doing one of the greatest disservices and harm to their local communities, State, and Nation now, than at any other time in our history. (and no, the Unions are NOT to blame.)