Obama -- who first spoke out for a nominee with "empathy" before a Planned Parenthood audience in 2007 -- rekindled conservatives' wariness over the weekend with his speech at the University of Notre Dame, calling for "fair-minded" dialogue and "common ground."

Charmaine Yoest, president of Americans United for Life, found Obama's speech at Notre Dame troubling in light of the names at the top of his short list. "He continues to want to use rhetoric to describe a mythical common ground while at the same time pursuing a real radical actual agenda," Yoest said. Her group recently released a report criticizing possible nominees such as Solicitor General Elena Kagan, appellate judges Sonia Sotomayor and Diane Wood, Homeland Security Secretary Janet Napolitano and outgoing Georgia Supreme Court Chief Justice Leah Ward Sears.

Across the aisle, neither the Planned Parenthood Action Fund nor Democrats For Life would speculate on how the issue will play out with no nominee yet announced. Democrats For Life Executive Director Kristen Day said she would "like to see someone a little more moderate on the abortion issue," but declined to comment specifically about Obama's short list. "When he picks his nominee, we'll talk to pro-life Democrats and formulate an opinion about where we are," Day said.

New polling shows Americans shifting to the right on abortion. On Friday, Gallup reported that more Americans consider themselves "pro-life" than "pro-choice" for the first time since the polling company began asking the question in 1995. In addition, new numbers from the Pew Research Center show support for legal abortion falling. Gallup concluded that "the dominant position on this question remains the middle option, as it has continuously since 1975: 53 percent currently say abortion should be legal only under certain circumstances."