Hard to answer questions honestly when the initial supposition is so far fetched (at least as it stands now).
Cain has won some straw polls (one of which he won with fewer than 400 votes), but do any legitimate polls (oxymoron?) show him with more than 10% support?
Yesterday's nationwide Fox poll has him at 17%, just 6 behind Romney; today's SurveyUSA for Florida has it Romney 25, Cain 22.
So, to answer your question... yes.