There is no such thing as a necessary evil.
The reason we have such awful politicians (and somehow even more terrible alternatives) is only because we voted for them. If you feel the need to vote, find someone you think is worth voting for. But don't settle for any flagrant disregard for human life and dignity because you've found a form of it incrementally more to your liking than what's currently in office.
Things don't have to be this way. They really, really don't. They only are because we allow them to be.