The Democratic nomination is going to be decided by superdelegates.
With re-votes in Michigan and Florida now all but impossible, it can be no other way. Pennsylvania has 158 pledged delegates up for grabs; after Pennsylvania, the total available is 415, for a grand total of 563 pledged delegates remaining. My best estimate of pledged delegates shows Obama with 1,419- still needing 605 delegates to get to the 2,024 mark required to secure the Democratic nomination. Clinton lags well behind Obama on pledged delegates. Neither candidate can win the nomination without superdelegates.
The question now is: how many superdelegates are needed?
Well, let's dispose of the remaining pledged delegates first. My current estimates- which still stand, pending better data- show Clinton netting a meager eight delegates from Pennsylvania, Obama netting five delegates from all the other remaining contests combined. In other words, it looks like they'll split the remaining pledged delegates about evenly.
Since the question is now superdelegates, let's go ahead and do just that- make an estimate to see how many superdelegates each candidate needs to win the nomination, presuming an even split of pledged delegates henceforth.
Half of 563 is 281.5; we'll give the odd delegate to Clinton.
If the remaining pledged delegates split dead even this way, that gives Obama 1,700 delegates to Clinton's 1,531.
Now let's factor in those superdelegates who have already endorsed Clinton or Obama. Based on an average of five different sources, I show Clinton having about 247 superdelegates endorsing her to Obama's 211. Add those to the above total, and Obama goes up to 1,911 total delegates, Clinton 1,778.
With the above estimate, there are currently 337 superdelegates remaining in play, of whom about seventy have not yet been chosen- unpledged delegates who are named by each state party, either by executive committees or conventions depending on state.
Out of that 337 total, Obama only needs about 113, or about 35% of the remaining superdelegates, to clinch the nomination.
Clinton, on the other hand, would need 246- over 70% of the remaining superdelegates- to clinch the nomination.
I'll be monitoring this website to see where superdelegate endorsements go, and I'll make irregular updates as things develop. For now, though, the magic number for an Obama nomination is 113 superdelegates. If he gets more than that in new endorsements from this point forward, the last door to a Clinton nomination slams shut.
That, of course, presumes an even split of pledged delegates henceforth (not guaranteed); it presumes no defections from either camp (not guaranteed); and it ignores the probability that the number of superdelegates will change, as it has done several times in the past two weeks (definitely guaranteed). As those factors change, they'll be worked into the estimate, too.
Here's hoping, eh?