A Brief Comment on Newt Gingrich

Have you ever noticed that columnists refer to other candidates by their last names, but Gringrich is generally referred to as "Newt"? Why is that? Is it because Newt is a sufficiently unusual name to be memorable? (Much more so than, say, Sarah, Michelle or Herman, let alone Rick). Or is it because they have a certain familiarity with Newt that they lack with other candidates?