The most reasonable quick summary of the facts is given by, believe it or not, Dick Morris. It would tear the party apart not to nominate an African American with the most elected delegates, and the Democratic system of proportional representation makes it impossible for Hillary to catch up on that front. Not only that, PA was Hillary country, in part, because of the closed primary and the very elderly electorate. NC and IN will have open primaries and considerably younger voters. Obama’s strengths are among the young and the independents, which is why, of course, he remains the stronger candidate against McCain. Each party is going to nominate a candidate who didn’t really win the support of its rank-and-file.