One Thing I've Noticed About Catholics During This Presidential Campaign ...
... is that there seem to be very few uncritical supporters of Sen. McCain among Catholics who may end up voting for him (in fact, some of us conservatives have have been so critical that we have refused to come out in support of his candidacy), but the support among Catholics who intend to vote for Sen. Obama seems to be completely lacking in any criticism whatsoever.
Conservative criticism of where McCain falls short of Catholic teaching runs rampant, and the support for his candidacy appears to be of the "hold-my-nose-and-cast-my-vote" variety. I haven't seen the same sort of criticism from Obama's Catholic supporters (with one exception) regarding where Obama falls short on Catholic teaching; in fact, I've seen Obama's Catholic supporters try to square Obama's position on abortion, for example, as a legitimate position that Catholics can and should support (see, e.g., Gerald Campbell, Morning's Minion, Doug Kmiec, etc.).
The argument from those Catholics supporting Obama instead focuses exclusively on where Republicans have fallen short on Catholic teaching. I won't argue with them in that regard (although I do believe their whole "Republicans have done nothing on abortion" meme falls flat and is easily rebuttable by the facts). But their argument rings hollow as long as they're willing to uncritically support a candidate who is so wholly lacking in some key areas of Catholic teaching.
At least be willing to vocally criticize your candidate - in no uncertain terms - where he falls short of Catholic teaching. Don't make excuses. Don't point fingers at the other side. Acknowledge that he is VERY BAD on issues like abortion and same-sex "marriage". Criticize him for it. Harshly. Obama and the Democrat Party have no incentive to change their anti-life policies if they can expect your uncritical support regardless of these shortcomings.
By the same token, those Catholics supporting McCain should continue to harp on ESCR and other areas where their candidate and his party are out-of-step with Catholic social teaching. But at least you've done a better job of it, to date, than those Catholics supporting Obama.