We know which type of candidates that Santorum endorses.
In 1996 he endorsed Arlen Specter for president, Specter was running to remove pro-life from the republican party platform, Santorum tells us that he himself was pro-abortion until he started putting together his run for Congress.
In 2008 of course, Santorum felt that Mitt Romney was the man who was superior to the pro-life, more conservative candidates.