From a Gallup poll released today:

The number of Americans who consider themselves pro-choice is up slightly ahead for the first time since 2008. Respondents are closely divided with 49 percent now labeling themselves “pro-choice” and 45 percent identifying as “pro-life.” Between 2009 and 2010 as many as 51 percent of respondents believed themselves to be pro-life while only 42 percent identified as pro-choice.

However, 51 percent of respondents answered that abortion is a morally wrong practice when questioned about ethical implications of abortion. Only 39 percent of those polled believe abortion is morally acceptable.

Among other things, this illustrates the fact that many people do not connect their moral views with legal enforcement. The basis of their reasoning, of course, is another matter.