Earlier quoted context omitted.
Your source does not support your claim that "close to half of American women do not support abortion."
46% of American women "pro-life", how is this not close to half?
46% may reasonably be described as close to half, but the details on the support for legal abortion in the poll (both on the page you linked and the additional information from the poll linked from that page) is inconsistent with the idea that "pro-life" identity equates to not supporting legal abortion, as the proportion of the population opposed to legal abortion is much less than half the proportion identifying as "pro-life".