All they need to do is to say, "I am a devout practicing Catholic and my position on Abortion mirrors that of my Church. If that bothers you, then don't vote for me."
If they are protestant, then they might have a more difficult time since Protestant Churches are all over the map on the issue.
If you are a Protestant, I think all you need to say is something like you do not believe that children should be punished for the sins of their parents. Hard facts make bad law. Exceptions for Rape or incest and the hard facts. Killing the child because of the circumstances of it's conception is murder.
The problem is they dance around the issue and sound apologetic. They need to take a hard stand and then challenge the questioner with something like "Do you believe in the death penalty for children conceived in difficult situations?" "Do you believe that children who are anticipated to be burdens to their parents should be executed". Those sound bites will never make the news.
I have a different take on it. I think they get into trouble because they try to answer the questions honestly. They should be smart enough politicians if they are the candidate to answer along the lines of "Roe v. Wade settled the issue", or "this is such a complicated issue it should be resolved on a case by case basis by those most closely involved".
I think in both cases where we might lose the candidate answered from an intellectually honest and consistent position, but they were dumb answers politically. The end result may be the Rats keeping the Senate and if Romney is elected nothing getting done.