"I'm not running for pastor in chief," Romney told ABC News' "This Week with George Stephanopoulos" Sunday. "I'm running for commander in chief." The interview with the candidate and his wife Ann was videotaped earlier.
Romney, the son of a former presidential contender and Michigan governor, the late George Romney, has said he would announce his candidacy formally in Michigan Tuesday.
If elected, he would be the first Mormon president.
Romney has changed his position on a number of issues before running for the White House, particularly abortion.
A former abortion rights supporter, Romney has taken a 180 degree turn: "Abortion is taking human life. There's no question but that human life begins when all the DNA is here necessary for cells to divide and become a human being. Is it alive? Yes. Is it human? Yes."
Romney said he would leave the issue of punishment for abortion up to the individual states.