Who is the Manchurian Candidate?

I just came across another reference to some people's fear that Barak Obama is a Manchurian Candidate who, after being elected, was going to be revealed to be under the control of enemies of America. It suddenly occurred to me how strange it is that those fears attach themselves to Barack Obama and not John McCain. After all John McCain was a captured prisoner of war being tortured by evil Communists for five years, presumably the situation in which Manchurian Candidates are created. Ever since his return from Vietnam McCain has seemed to be under an overwhelming compulsion to be president. He immediately divorced his wife who had waited faithfully for him during his imprisonment and married a woman with wealth and connections that enabled him to enter politics. The last few years he has shown himself willing to compromise everything he has ever stood for in order to get the presidential nomination. If someone had been programmed to become president as part of some nefarious plot isn't that exactly how he would act?