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?
That's what the bottom line if for you??? If Romney (as most Mormons) considers himself a Christian and you don't you'd vote against him on that basis???
When Ezra Taft Benson was Sec. of Agriculture under President Eisenhower, (later was president and prophet of LDS Church) upon starting his service in this office, he suggested starting each cabinet meeting with a prayer. President Eisenhower agreed to the suggestion and kept the prayer as the opening event to every cabinet meeting during his administration.