It was INTENTIONAL in case of Santorum. He has been working WITH ROMNEY. Another big negative against Santorum is that he is a radical fiscal socialist. So you cannot equate him with someone who although part of the establishment has in the past has contributed to cutting down spending.
Newt's objective was not to split the conservative vote so that Romney would end up with the nomination. Santorum's objective clearly was to help Romney become the nominee.