Doesn't matter if he takes some from Santorum, as long as he takes enough from Romney. It's the Newt+Santorum total that needs to be enough to have Romney not get 50% + 1 of the delegates.
Well, by my count, he’s not taken delegates from Romney, He’s cost Santorum significant delegates. Lost in MI, OH, WA, WY and AK were all winnable but became close wins for Romney.
What delegates has he actually cost Romney at this point? Florida was WTA.