Well, first of all, I haven't ruled out voting for a Mormon. (You'll note that at least on the prayer issue, and on another thread, the issue of presidential discernment, I DO make a huge distinction between a Mormon candidate for president and a Mormon candidate for other offices)
Secondly, we never vote (or not vote) for someone in a vacuum. In this way, I respect folks who are genuinely wrestling w/who to vote for come Fall of '08. (I have, to be frank, less respect for those who are outright pushing Mitt for the primaries in '08).
Would I vote for a Jew? If he is a practicing Jew, I would assume he prays to the same God of Abraham, Isaac, and Jacob...a God, by the way, who is Trinitarian even if not perceived that way by such a president.
Prayer in the oval office in a crisis is not the only presidential consideration of a faith nature.
If a president shows he/she is vulnerable to deception in the most important area of his/her life (his/her faith), then what does that say about his/her discernment skills in every other aspect of that person's life?
Also, in terms of foreign policy & national security issues, if a person cannot properly define what true Christianity is, then on what basis do we expect him/her to properly define what is Islam or radical Islam or jihadic Islam or Wahhabi Islam? What implications does that have for dealing properly and realistically with Allah-based terrorists?