I don't think the blockchain is going to protect you from a maniac with a wrench "convincing" you to vote the way he likes.
Being coerced into voting for a certain party is a whole different problem, with different actors. You're not going to run the election again when the spouse of someone pressured them into voting against their will. How would you even want to prove it had happened in the first place? There's not going to be a paper trail without giving up voter secrecy, which is yet another problem.