I disagree. It is unwise to limit a campaign.
If either Santorum or Newt reach >50% in the state level or congressional district levels, he will collect ALL the allocated delegates leaving none for Romney.
If they both campaign for the same delegates at the same CD or state, they will never achieve >50% votes, therefore, the allocated delegates at that particular CD or state will be awarded proportionally to all three candidates plus Ron Paul.
Unfortunate!