Many western European Jews of the late 19th century believed that emancipation was possible. They could be citizens, practice their religion, and even change religions if they liked. Conversion was chosen by many who saw it as an escape from the remaining anti-semitism. All of this ended, of course, when the Nazis made anti-semitism a matter of "blood" and "race".
I had always thought that the American "one-drop rule" was insidious. Unbeknownst to most of us, we carry genes from many "races". We do make formal and informal choices with respect to cultural identification.
What to make of Barak Obama and the hoopla surrounding his candidacy? He is a standard-issue liberal, circa 1965 (with some JFK-type charisma). Not much "change" there.
The celebration has to do with the fact that many identify him as "black" or "African-American". But his post-racial appeal (and his chance at victory) rest on just the opposite, that he is a mixed-race-mixed-background man free to define himself in ways that rise above the tired stereotypes.
There are two things that get in the way. One is the First-Trinity of Chicago crowd and the other is all the hoopla over the first "black" candidate. He and his supporters have to distance themselves from one-drop rule thinking and all the one-drop rule people -- many of whom are among his supporters.