The purpose of elections is to put people in office with whom we hold common views. To get elected these people have to buy TV time, and to do that they have to accept money from wealthy people, usually corporate executives.
That means that even though they side with us on the ground on important issues, our people can’t actively work for our issues while in office, or they will lose their corporate funding to an opponent.
But still, it is important to have our people in office, as the opposition are even worse people!
This is American politics in a nutshell. It is important to get your candidate in office. If that person is liberal or progressive, she cannot be effective while in office for fear of losing funding to an opponent. The only important thing is to keep her on office. Right wing candidates, on the other hand, are free while in office to be as wacky as they want to be, and never suffer loss of funding.
If you don’t vote, you don’t matter. If you do vote, you still don’t matter.