Some Catholic politicians have tried to have it both ways. They have even tried to gain favor among their fellow Catholics by noting their strong opposition to capital punishment, which puts them in an oddly inconsistent position. Such Catholic politicians favor preserving the lives of convicted murderers, but choose to do nothing when they have the power to stop, or at least curtail, the killing of the innocent unborn.
While I am not a Catholic, it seems more than inconsistent to take such a position. One chooses one's denomination, just as one chooses one's political affiliation. No one forces another to become a Catholic and no one requires one to become a Democrat, or Republican. Judicial nominees have been denied confirmation based on their membership in clubs that excluded blacks and Jews. But now we may be about to elevate two men to our highest offices who would deny civil rights to African American babies (who are aborted disproportionately to other races), one of whom seeks the votes of his fellow Catholics.
Two years ago, Pope Benedict XVI reiterated the church's "non-negotiable" issues: "Protection of life at all stages, from the moment of conception until natural death; recognition and promotion of the natural structure of the family as a union between a man and a woman based on marriage; the protection of the rights of parents to educate their children."
Obama and Biden oppose at least two of these (they claim to be against same-sex "marriage," but for "civil unions"). Whether the TV ads change any minds may be problematic. Catholics who are enamored with "change" and the belief that government is the primary instrument of God, rather than the church, in carrying out His will - and who have ignored church teaching on profound moral issues - are unlikely to be swayed by further appeals to become "truly Catholic." But if only a few see where an Obama-Biden administration would take the country on moral issues, in a close election that might be enough.