On June 15, Rasmussen Polls released a poll for the U.S. Senate race in South Carolina. See it here. It shows 58% for Republican Jim DeMint, 21% for Democratic nominee Alvin Greene, 9% for “some other candidate”, and 13% undecided.
The only other person on the November ballot is Tom Clements, Green Party nominee. It appears Rasmussen did not actually list him, yet apparently 9% of the voters still opted for “some other candidate”, rather than letting themselves be listed as “undecided.” None of the newspaper stories about this poll even mention Clements.