The origins of the term, "American exceptionalism" and its use in American political rhetoric are the subject of an article by Terrence M. McCoy,  Gordon Grey Fellow of International Journalism at Columbia University, in the March 2012 issue of Atlantic. 

This phrase has been stated often in the ongoing 2012 presidential  primary campaign.  It  actually originated with Joseph Stalin in 1929 and was not a compliment. It gradually faded from use.  Terrence McCoy turned to the archives of the American Presidency Project's website to determine when it began to reappear in presidential speeches.  The answer:  In the 1980s, "charged with a new connotation of national superiority. "

The entire article ca be viewed online at http://www.theatlantic.com/politics/archive/2012/03/how-joseph-stalin-invented-american-exceptionalism/254534/.

The American Presidency Project (http://www.presidency.ucsb.edu ) is an award-winning website created and maintained by UCSB political science Professor John Woolley and Gerhard Peters, and is widely used by scholars and others interested in the presidency and American political history.