Those are some interesting numbers but since you don't provide a link, a poll name or a date, I have absolutely no idea where they came from. I've got some relevant numbers right here:
ABC News/WaPo Poll 8-19-22/08 Abortion should be:
Legal in all cases-22%
Legal in most cases-32%
Illegal in most cases-26%
Illegal in all cases-18%
Time Poll 7-31-8-4/08 Abortion should be
Always legal first 3 months-48%
Legal in certain circumstances-40%
Illegal in all circumstances-10%
Now you will notice in both polls, a healthy majority of the American public believe abortion should remain legal in at least some circumstances. However, more relevant to this debate, only 18% in the ABC News/WaPo poll and 10% in the Time poll feel abortion should be made completely illegal in all cases or circumstances, this is the position held by Gov. Palin. That is why I suggest, once her extreme anti abortion views (no exception for rape or incest) are thoroughly made public, many Clinton voters that otherwise might have given her look now instead will be given pause.
http://www.pollingreport.com/abortion.htm