Mostly reading along here, but I thought I'd post a link to Polling Report's page of opinion polls about abortion.
http://www.pollingreport.com/abortion.htm
The ghist of it seems to be this:
(a) To the extent that Americans express an opinion, they are split more or less 50:50 between 'pro choice' and 'pro life'.
(b) A majority of Americans wants tougher legislation on late term abortions.
(c) A majority of Americans -- certainly not the same as in b) -- wants to uphold
Roe v. Wade. This Supreme Court decision permits curbs on third-trimester abortions, regulations for the mother's health during the second trimester, but no regulation during the first trimester, when most abortions occur.
(d) A majority of Americans opposes a recent anti-abortion law in South Dakota, which prohibits all abortions, except those saving the life of the mother.
(e) It isn't clear which way the trend goes. Some polls find a trend towards pro-life over the last 10 years, others find one towards pro-choice. The most likely interpretation, in my view, is that Americans have made up their minds about the issue, and they aren't changing them much over time. Independent of that, there is something unexplained going on at the pollsters to make them find trends that aren't there.
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Putting all this together, I can see the Republicans winning elections by advocating incremental restrictions on abortion. But I just don't see how advocacy against contraceptives can possibly do them more good than harm.