I linked
this list of polls because it lets you compare wordings and options. I particularly the like the most recent Washington Post/Kaiser Family Foundation Poll options;
"Do you think abortion should be legal in all cases, legal in most cases, illegal in most cases, or illegal in all cases?"
Results: 19/36/25/17, 3% unsure.
So that's 17% saying illegal in all even when given the 'illegal in most' option. There is a similarly worded Pew poll down the page that shows similar results; 16% taking the illegal in all option. Finally there is the Virginia Commonwealth University Life Sciences Survey from 2010 that explicitly asked about rape. The wording;
"Which of these comes closest to your views about abortion? A woman should be able to get an abortion if she decides she wants one no matter what the reason. Abortion should only be legal in certain circumstances, such as when a woman's health is endangered or when the pregnancy results from rape or incest. OR, Abortion should be illegal in all circumstances."
This pushed the percentage of those saying illegal in all circumstances down... to 15%.
The
Gallup numbers are actually worse. The latest (2011) poll asking solely about cases of rape or incest showed 22% saying abortion should be illegal in those cases. It also showed 15% opposed when the woman's health is at risk and 13% opposed
when her life is endangered.