Obama finds it tough to answer abortion question and regrets answer

It was easier for Joe Biden to answer the abortion question. But why was it a tough question if you claim to be a Christian. I wonder if Obama is trying to weigh the reactions of the people first.
Joe Biden gave a good answer:

A Roman Catholic, Biden said he accepts his church's teachings that life begins at conception, but that the issue is personal for him. He said it wouldn't be right to impose his views on others who are just as religious as he is.
"I'm prepared as a matter of faith to accept that life begins at the moment of conception. But that is my judgment," Biden said on NBC's "Meet the Press." "For me to impose that judgment on everyone else who is equally and maybe even more devout than I am seems to me is inappropriate in a pluralistic society."

Source: Click here.