Should our limited resources for species protection be focused on species that are at the highest risk of extinction?

Saving Species from Extinction:  Should our limited resources for species protection be focused on species that are at the highest risk of extinction?  Some argue that high-risk species are less successful products of evolution and should not receive extraordinary protection; consequently, all species at risk of extinction should be equally protected.  When selecting which side of the issue to be on, cite reliable scientific resources/reference to support your stance on this issue.