The "none" option has been on the ballot in Nevada since 1976. It applies only to statewide races.
Republicans sued to get it stricken from the ballot in 2012, fearing that "none of the above" could siphon votes from a disgruntled electorate and sway the outcome of a close presidential race and Nevada U-S Senate contest.
While the "none" option can never win an election, it has played a role in determining the outcome.
Two years ago, Republican U.S. Senator Dean Heller defeated Democratic challenger Shelley Berkley by about 12,000 votes. More than 45,000 votes were cast for "none."