Ebarnacle.

Yes I reckon you would have to have a majority to vote "none of the above"

However, this comment "It would also require that there be voters preselected as electors who would be willing to vote that way." makes no sense.

All it requires is to give the electorate the choice to reject all the available candidates.

Then you rerun the election.

To prevent this process being reenacted indefinitely, political parties wwould have to field candidates that people actually want.