Halperin says that 17 percent of West Virginians think that Clinton should drop from the race.
If everyone who believed this was an Obama supporter, and 60 percent of Obama's supporters believed this, that would imply that Obama got about 28 percent of the votes.
Anyway, there are few silver linings for Obama in the exit polling data, and there are a lot of talking points that will frustrate his campaign for a couple of days. As I've said before, the best thing the campaign could do would be to change the subject by rolling out some particularly interesting superdelegate endorsements tomorrow.
UPDATE: Okay, we can do some better back-of-envelope stuff. Clinton won the commander-in-chief question 68/29. The AP data I linked to above says that about 1 in 10 Obama supporters said that Clinton would make the better commander-in-chief, whereas "very few" Clinton supporters said that of Obama.
If we assume that 2 percent of Obama's commander-in-chief points came from Clinton voters, that leaves 27 percent that came from Obama voters. If 27 percent represents 90 percent of Obama's support, that means he got about 30 percent of the state's vote.