To beat Romney, it makes sense if Santorum concentrates on Michigan - where he's stronger - and Newt on Arizona, where he's stronger.
Michigan is Winner-Take-All by Congressional District - so if Mitt won 35% to 34% in every district he would win nearly all the delegates; at-large delegates are split proportionally.
Realistically, (IMO) Newt has no chance to win more than 1 or 2 delegates in Michigan, so he's trying for Arizona which is true winner-take-all.
Thanks for the input. Answered some questions for me. Thanks again.