UPDATED AT 9:45PM ON APRIL 26TH
I have now had a change to update the superdelegate predictions. As always, I use information about the superdelegates who have committed to a candidate to generate predictions for the remaining unpledged superdelegates. I exclude superdelegates from DC and the territories because we lack complete data from those areas, and from IL, NY, and AR because superdelegates in those states have nearly unanimously cast their support for their native son/daughter. As always, information on the superdelegates is provided by the Democratic Convention Watch site. You can find more about the methodology I use here. Since I began generating these predictions, 106 superdelegates have announced their endorsements, and we have been correct on 74 of these. Thus, overall, the models have been correct 70% of the time.
In addition to adding the newest endorsements to the model, I have also added information about the add-on superdelegates who have been designated at this point. We are unable to predict how most add-ons will vote since we don't know who they are yet. But I added those who have been selected to the model (most add-ons have already endorsed one of the candidates).
In the figure below, I present the distribution of unpledged superdelegates based on the probability of supporting Clinton:Superdelegates who are between 40% and 60% likely to vote for Clinton/Obama are labeled as "unclear." There are 77 superdelegates in this range. There are 129 unpledged superdelegates who are at least 60% likely to vote for Obama; just 38 unpledged superdelegates are at least 60% likely to vote for Clinton. These predictions suggest that unless something dramatically changes, Obama will be able to cut into and even overtake Clinton's superdelegate lead in the coming weeks and months.
The estimates for each unpledged superdelegate are listed here. These estimates show that among Obama's most likely endorsers are Rep. Dennis Moore (KS), Rep. Michael Michaud (ME), and Rep. Tom Allen (ME). Clinton's most likely endorsers include Reps. Jerry McNerney, Susan Davis, and Lois Capps (all from CA).
UPDATE: I updated this information to reflect that fact that my original data had Patrick Lynch as undeclared (when he has, in fact, endorsed Obama).