And he drew attention earlier this fall when he said in Iowa that laws restricting access to abortion would not be a priority if he wins the White House.
Under pressure from some conservatives, he reaffirmed his opposition to abortion in most cases the next day.
The Supreme Court has split 5-4 in recent years on some abortion-related cases. With several justices in their 70s, the next president may well have the opportunity to name one or more replacements.
Associated Press writers Ken Thomas and Charles Babington in Washington contributed to this report.
Follow Kasie Hunt on Twitter at http://www.twitter.com/kasie and Steve Peoples at http://www.twitter.com/sppeoples
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.