How Do Christians Choose a Candidate?

With Giuliani as the Republican frontrunner, the question arises, "Can I, as a Christian, vote for a man who is Pro Choice?" It has been suggested to me that we are not voting for a pastor, but a president.
Yes, we are to respect the office of the president whether we agree with the president or not. As Christians we are to understand that God put all authority in place. Even though we are not electing a pastor and we are to respect the office, the decision to me has got to be more about the man than not. Someone might say, "So he is Pro Choice, look at what a political conservative he is." All I can say to that is, wow!
I know that it is impossible to legislate morality. For instance if we ban abortion are the girls not going to get abortions somewhere other than clinics with trained professionals? (By-the-way, I do believe that we should ban abortion and that it is murder.) Morality is a heart issue and only Jesus Christ can change hearts.
I want a man that has impeccable moral values. Not a man that has been married three times and believes in abortion. So, I therefore must choose to vote for the candidate, if there is one, who claims Christ as a member of the triune Deity of God and as that candidate's personal Lord and Savior. I want a man who is not afraid of losing political gain, to speak out against abortion, gay marriage, and other sins against the Truth, Jesus Christ. Someone who is not afraid to give up a second term in the name of what is true and right.
Perhaps if he has traveled this far in politics, then he has already compromised along the way. I choose to believe that we can find this man and that God is faithful to His children regardless of who is in office.