The root cause of the slow decline of our political system into a system that accomplishes nothing besides giving the wealthy and powerful more money, is neither the stupidity of the Republicans or the weakness of the Democrats, it is the system itself. As the below presentation, by scholar and political activist Larry Lessig, will describe, the root problem is that the incentive structure of our political system encourages politicians to consider the desires of their wealthy donors before the needs of the People they represent.
Link to the above video if its not working here.
I honestly believe that this is the most important issue of our time. If we can get our Republic back, then it will be much easier to solve all of the other issues that we care about. Think about Congress's recent inability to actually make meaningful decisions on the issue of gun regulation. If our government was only dependent on the People it represents, then it would almost definitely support policies which 90% of the population supports. There are many more examples, but this is perhaps the most recent and obvious.
If you would like to support the effort to fix our Republic, so that it represents the People instead of the donors please join Rootstrikers and support the American Anti Corruption Act. If you want to learn more, I found that Lessig's book very clearly described the situation.