Don't take this as an endorsement of a pro-choice candidate, just a way John McCain could make it work should he choose to go in this direction...
Imagine if this is Joe McCain standing on stage without a podium and gives the following speech:
"My Fellow Americans...this election, this year, this time in American History is a rare time and one that My Friends calls for a rare moment in Presidential Politics. You see, My Friends, America is at war. It's at war against people that don't have a flag on their shoulders but hatred in their hearts. Hatred that causes them to fly planes into buildings and strapping bombs on innocent children just to kill innocent people. That's why, My Friends, at this time we need to put politics aside and why, My Friends, I have chosen (Insert Pro-Choice Tom Ridge, Joe Lieberman or Rudy Giuliani) as my choice to help me these next four years to protect America. My friends, we heard this last week how we need Change from the Democrats. My friends, I disagree, we don't need a change from seven plus years of no terrorist attacks against us on our soil. My friends, we don't need change from taking the fight to them on their soil instead of having a dirty bomb go off in New York, Chicago, Los Angeles or Dallas. My Friends, the change we do need is to put the partisan politics aside we heard about in Denver and instead put America first, our national security first, and protecting America first. (VP Candidate) and I are running to put America First. "
Again, this isn't an endorsement but a strategy. Imagine if John McCain comes out and says I am running for four years to focus on National Security and I've chosen the best national security candidate for VP. Just a thought, but it might be the home run he is looking for. When George W. Bush ran for Governor versus a popular Ann Richards, he repeatedly stayed on message and stuck the three issues he was running on...so much Ann Richards became discombobulated and lost her cool and eventually lost the election. Obama is already beginning to crack, now it's time to push him harder.
Being an evangelical Christian who is staunchly pro-life, a Choice of any of these three would keep me from wanting to actively walk/knock/phone for a John McCain campaign. This reminds me of the line from "A Few Good Men," when he says it doesn't matter what I believe, it matters what I can prove. In politics at this level, it doesn't matter what someone wants, it matters what gets them elected.