One doesn't know where to cross (8,5)
I believe the answer is:
floating voter
If this is the answer, I'm afraid I cannot explain it.
Can you help me to learn more?
(Other definitions for floating voter that I've seen before include "Inconsistent type at the polls" , "One who may be swayed either way at election time" , "One without political affiliation" , "One whose political allegiance might easily change" , "political chameleon" .)