In 2012 I voted against Obama because I thought he was too conservative. I didn’t think his healthcare program went far enough, I didn’t like his foreign policy of continuing the Bush wars, and I thought he turned out to be far more establishment than he had indicated as a candidate in 2008.
I voted for Jill Stein. I said it wasn’t a protest vote and that I was voting my conscience, but it was totally a protest vote. Stein would have been the worst president in US history, and I even knew that at the time. I did it because Obama had a predicted 99% chance of winning my state, so I figured it was safe and would communicate to the democrats that there was a preference for more left leaning candidates.
What I did not do was try to campaign for Stein to try to get swing state voters to vote for her. I didn’t try to get swing state voters to not vote.