I think they should run together. At a certain point, the trailing candidate can drop out and toss his delegates to the leader and the leader can announce that the other candidate will be on the ticket as VP.
Your biggest problem with that theory is, most of us who support Newt, don't want Santorum anywhere near the Office of the Presidency. For SEVERAL reasons.
Santorum has been in this for over a year now, and for most of it, he was completely shunned, and overlooked for reasons that belong to who and what Santorum is. Now all of a sudden, he is the ONLY choice to win?
Not even close. The damage has been done and the disaster some of us predicted, has become a reality.