I don't think NSA meddles in politics. CIA sure. NSA is more about communications, hacking, signal intelligence and spying in general. They give you the information. If you want to do dirty stuff with that info, the CIA is there for that.
NSA collects who you're voting for and everything else you've ever said online in case they need to invent a reason to black-site you.
FBI convinces the autistic son of your Pakistani neighbors down the street his life only has meaning if he becomes a Jihadist.