My guess is it's really 46% Clinton, 53% Anyone-But-Clinton and 1% undecided, but will vote for any Democrat on the ticket.
As a resident of NYC, and a graduate of Barak Obama's alma mater, I would suggest that "1% undecided, but will vote for any Democrat on the ticket" estimate is low. About 80% of liberals (20% of the electorate) will never forgive Clinton for backing the Iraq war. And for continuing to oppose Obama in the primaries after he had already been anointed.