Cause he’s under the mistaken notion that he can win with just the hardcore conservative voters that aren’t subject to ABO syndrome. So he’s trying to peel off Santorum votes, but it will never be enough. Santorum attracted others including the ABO crowd. That’s what made him a contender with Romney. Even if Newt could put Santorum in 3rd again, he’ll never beat Romney.
I think this is the correct scenario. Ultimately though, our little Republican primary voters are just unwilling to buck McPain, Dole, and GHWB. They need "assurance" that they are doing the right thing in backing Mittens.