If you are too disgusted with your democrat option to vote for them (I assume no one is following me who would vote for republicans?) Anyway I think it's helpful to still vote and write-in something or check out the local referendums and just vote on those.
Your null vote weakens republican and democratic mandates. Just telling people you feel that way is ... less impactful.
It also increases overall turnout numbers which mostly freaks out all of the right people.
@futurebird Honestly I don't agree. They don't count null votes as being votes that are against them but also against their opponent. I think people give the system far too much credit for somehow voicing something. If you choose to throw away your vote, they don't even know that you did it. You're not punishing Democrats who aren't good enough, you're just helping let those who have zero standards (which generally means Republicans) win by default.