My vote is an amen or agreement with whatever law or person is being introduced at that time.
I think I will be judged more by my agreements than what the government may or may not do. If we don't keep just laws in our nation, how will we be able to vote a clear choice any longer?
Looking at the bigger picture, I also know that God will judge the nations by their decisions as a whole. What kind of decisions do we want Him to see us make?