Very good posts below, both Peter Nixon's parsing and Cathleen Kaveny's essay. Couple of additional reads to suggest--one a very welcome (IMO) piece by Bishop Blase Cupich of Rapid City, S.D in the latest America, titled "Racism and the Election." It is one of the only pieces I've seen from a religious leader addressing the ugliness emerging over the Obama candidacy. Money quote:

Last November the bishops issued Forming Consciences for Faithful Citizenship, the most recent of the documents we issue every four years during the teachable moment of our most important national elections to acquaint Catholics with their responsibilities in the forum of public policy. In that document we spoke of the things we must never do as individuals or a society because they are always incompatible with the love of God and neighbor. We cite the taking of innocent human life as one example of such intrinsically evil actions. Racism is another.In any election people have many reasons to support one candidate or to oppose another. Some of these reasons may be wise and good, some not so good, and others simply wrong. The promotion neither of abortion nor racism can ever be a motivation for ones vote. Voting for a candidate solely because of that candidates support for abortion or against him or her solely on the basis of his or her race is to promote an intrinsic evil. To do so consciously is indeed sinful. That is behavior incompatible with being a Christian. To allow racism to reign in our hearts and to determine our choice in this solemn moment for our nation is to cooperate with one of the great evils that has afflicted our society.

The other item is Denver Archbishop Charles Chaput's latest take on why a Catholic cannot vote for Obama (which seems to be the bottom line of his argument). He stresses that he is speaking only as a private citizen and author, but his voice obviously carries a weight beyond that. ("Chuck the Archbishop?!") Archbishop Chaput has been a strong proponent of the intrinsic evil of abortion governing all political choices, but he seems to be tougher than ever here, or perhaps it is the tone, and the fact that he is directly challenging Douglas Kmiec. Money quotes (via ZENIT, which has the text of the Oct. 17 address titled "Little Murders"):

Prof. Kmiec argues that there are defensible motives to support Senator Obama. Speaking for myself, I do not know any proportionate reason that could outweigh more than 40 million unborn children killed by abortion and the many millions of women deeply wounded by the loss and regret abortion creates.To suggest -- as some Catholics do -- that Senator Obama is this years real pro-life candidate requires a peculiar kind of self-hypnosis, or moral confusion, or worse. To portray the 2008 Democratic Party presidential ticket as the preferred pro-life option is to subvert what the word pro-life means. Anyone interested in Senator Obamas record on abortion and related issues should simply read Prof. Robert Georges essay of earlier this week, Obamas Abortion Extremism, at thepublicdiscourse.com. It says everything that needs to be said.Of course, these are simply my personal views as an author and private citizen. But Im grateful to Prof. Kmiec for quoting me in his book and giving me the reason to speak so clearly about our differences. I think his activism for Senator Obama, and the work of Democratic-friendly groups like Catholics United and Catholics in Alliance for the Common Good, have done a disservice to the Church, confused the natural priorities of Catholic social teaching, undermined the progress pro-lifers have made, and provided an excuse for some Catholics to abandon the abortion issue instead of fighting within their parties and at the ballot box to protect the unborn.