It could very easily be argued that Newt was always the real stalking horse for Romney. Mainly because nobody will wish to admit it.
But...he will get a pass around here, not that he should. LOL
I think Newt did to Santorum what Huckabee did to Romney in 08. Huckabee took enough votes away from Romney to lock up the nomination for McCain. Had Newt dropped out Santorum probably would of won Michigan and maybe stopped Romney. But Newt didnt owe anything to Santorum and had every right to stay in as long as he had funding to continue.
Of course thats just my opinion.