Your statement doesn't make sense to me, perhaps you could clarify it? Did you mean that 85% of the population didn't vote for the current leader of the executive branch? If so then perhaps "that 85% [...] did not vote for" might be more appropriate. Or were your referring to the electoral college used to elect the POTUS?

For the first, 100% of citizens cannot vote for the federal government representatives (children, most felons, etc do not have the franchise), and about 1/2 of citizens who are eligible to vote do not. The vast majority of adult citizens can vote.

For the electoral college, that only applies to the POTUS. I agree that the electoral college is deeply flawed. But both senators and congressmen are elected directly. They are the ones who make the laws. The executive branch just enforces and executes those laws. The responsibility for the many vague laws that hand over power to the executive is on congress.

IMO, to say "85% of Americans pay taxes to a federal government that they cannot vote for" is misleading at best.