The problem is, most of Romney's good states are WTA (either at-large or by district) so will only give a pittance of delegates to Santorum, while a lot of the big Santorum states are proportional (NC, TX, and PA has the directly-elected delegate thing) so Romney will still pull some notable support from them even while losing.
Yeah, exactly. One of Romney's strengths has been picking up relatively large proportions of delegates in states he loses and smashing opponents in delegate counts where he wins. Santorum hasn't been able to crush Romney and take a dominant amount of delegates often enough to catch him. And now with Romney likely to take big winner-take-alls down the road, I don't see a way he doesn't get a majority of delegates.