Well the next Dem debate will be more interesting if Bernie has decided to go after Clinton more aggressively. Of course there is a danger in that she has high favorables so even some of his own supporters actually like Clinton. Dems rallied to her side after the Benghazi hearing, if he starts saying some of the same things those guys on the committee were saying he could end up hurting himself more.
PPP's Iowa poll has Clinton's favorability at 49/30 with Sanders supporters. In New Hampshire, she's at 61/19 with Sanders supporters. Her favorables with all Democrats are exactly the same in the two polls so it looks like in NH Sanders has won over more people who like Clinton.
