The issue of NR just out weighs in on the issue:
The Susan B. Anthony List, a pro-life group, urged presidential candidates to take a pledge to enact various pro-life laws, pick constitutionalist judges, and appoint only pro-lifers to government posts relevant to abortion policy. All the Republican candidates save Herman Cain, [Jon] Huntsman, and [Mitt] Romney signed the pledge. Romney said that the pledge would force him to support cutting off government funds to all hospitals that perform abortion — something the organization denied — and that he would pick the best appointees for each position in his administration, all of whom would have to implement his pro-life views. The pro-life group then circulated another petition, this one for citizens pledging to support only those presidential candidates who had agreed to its demands. The drawback to the first pledge is that it may make pro-life politicians who sign it look weak, make pro-life politicians who do not sign it look as though they were not pro-life, and make the pro-life cause look like an albatross that has to be forced on unwilling candidates. The drawback to the second pledge is that it is, as written, absurd: It would block pro-lifers from supporting Romney over Obama in November 2012 because he has not made any commitments about the secretary of health and human services. The Susan B. Anthony List should itself take a pledge: to make sure it’s advancing its goals and not setting them back.