Republican presidential hopefuls Mitt Romney and Herman Cain have announced that they won't sign the Susan B. Anthony's List Pro-Life Presidential Pledge, which five other Republican contenders --Michele Bachmann, Newt Gingrich, Ron Paul, Tim Pawlenty and Rick Santorum -- agreed to sign.
Romney announced his decision in an oped today on the National Review's website. He called the pledge "overly broad" and said signing it could have "unintended consequences."
"It is one thing to end federal funding for an organization like Planned Parenthood; it is entirely another to end all federal funding for thousands of hospitals across America," Romney wrote. "That is precisely what the pledge would demand and require of a president who signed it."
Cain issued a statement today on why he choose not sign the pledge. While he said he "adamantly" supports the first three parts of the pledge -- appointing pro-life judges and selecting pro-life appointees to his cabinet and the executive branch as well ending taxpayer funding for abortions -- he has a problem with the last part of the pledge, which demands the signee "[advances]" the Pain-Capable Unborn Child Protection Act.
"As president, I would sign it, but Congress must advance the legislation," Cain wrote. "I have been a consistent and unwavering champion of pro-life issues. In no way does this singular instance of clarification denote an abandonment of the pro-life movement, but instead, is a testament to my respect for the balance of power and the role of the presidency."
Romney also said he is pro-life, but he didn't always feel that way, a fact Rick Santorum has pointed out on several occasions. In 1994, when running for the Senate against Ted Kennedy, he said, "I believe abortion should be safe and legal in this country." In 2002, during his bid for the Massachusetts governorship, Romney vowed to "preserve and protect a woman's right to choose."
"[Romney] obviously still has to be concerned with presenting himself as a conservative," ABC News political director Amy Walter said. "He has had a track record on abortion that does upset some voters. Some conservatives were not convinced of his conservativism on the issue, but it would do him little good for him to look dogmatic on an issue that he has already had a change of heart on."
How much will this decision affect Romney and Cain's presidential campaigns?
"The broader question is, what role will social issues play this year when the economy is front and center?" Walter said. "This might have been a bigger problem for some of these candidates in a different year, but I don't know that it will have the same impact this year.
"This is hypothetical right now, not reality," Walter added. "We know the reality of how the system works -- you can pledge to do a lot of things as president."
Susan B. Anthony List's Presidential Pledge:
One, only nominate to the U.S. Supreme Court and federal bench judges who are committed to restraint and applying the original meaning of the Constitution, not legislating from the bench;
Two, select pro-life appointees for relevant Cabinet and Executive Branch positions, in particular the head of National Institutes of Health, the Department of Health & Human Services, and the Department of Justice;
Three, advance pro-life legislation to permanently end all taxpayer funding of abortion in all domestic and international spending programs, and defund Planned Parenthood and all other contractors and recipients of federal funds with affiliates that perform or fund abortions; and
Four, advance and sign into law a Pain-Capable Unborn Child Protection Act to protect unborn children who are capable of feeling pain from abortion.
ABC News' Emily Friedman and Katie Slaman contributed to this report.