On Friday, a Quinnipiac poll had Sanders at 42%, Clinton at 41% and Biden at 12%. And that was considered huge. Huge news for the Sanders campaign.
This poll has Sanders at 43%, Clinton at 33% and Biden (who, by the way, is not actually running) at 10%.
It should also not be overlooked that Sanders is up by 22 points in New Hampshire. You cannot simply attribute that to local-boy-does-good. New Hampshire has been familiar with Hillary Clinton since 1992. They clearly prefer Bernie Sanders.