One way to look at it:
The designer of the typeface used by Obama, Gotham, is one of the United States greatest living type designers (seriously, there is a renaissance in type design happening right now and Toby is one of the leaders). Gotham is simultaneously urban and working class but also high end as well. It was carved on the cornerstone of the new World Trade Center complex but is based on urban san serif type made by local sign shop guys. Toby is a native New Yorker.
John Baskerville (Clinton's type choice) lived during 18th Century in England. Baskerville is respectable but conservative and more an early 1990s choice.
Optima (McCain) was designed by Hermann Zapf, a well regarded soft spoken German type designer known for his calligraphic inspired type designs. Zapf is 90 years old and still hard at work (like McCain?)
All about Gotham here: