I watched the debate pretty closely, and in my opinion, both candidates did pretty well and it was mostly an even contest. (Note: I am not committed to one or the other candidate, I happen to like them both.)
Sanders did very well in getting his message across, but he demonstrated weakness in foreign policy.
Clinton did a good job at addressing the alleged Wall Street ties and addressing the email issue.
But there is another way to answer the question. How much did each candidate strengthen their own support, and how much did each candidate do to convince undecided individuals to prefer them, especially those individuals in New Hampshire?
One way to asses that is to see what happens next Tuesday. As previously discussed, Sanders is expected to win the New Hampshire Primary by about 20%. If, in the end, he falls short of this, then perhaps Clinton did a better job of convincing undecideds to pick her. If Clinton does worse than 20% down, then perhaps Sanders did a better job of convincing undecideds to pick her.
Meanwhile, we have the online polls. Across a range of polls, Clinton gets number in the 10% – 20% range, and Sanders gets numbers in the 80-something% range. It has been suggested that Sanders supporters are better at gaming the on line polls than Clinton supporters. With numbers like this (8:2) that is almost certainly what is going on. Or, at least, it is a reasonable hypothesis. It is also possible that Republicans are clicking on Sanders because of the widespread belief among anti-Democrats that Sanders is the candidate the GOP prefers to run agains, even though the evidence for that is rather weak. In any event, an 8:2 (or, really, closer to 8.5-1.5) ratio does not accurately reflect the Democratic voter’s position. It is poll gaming of one kind or another. Does poll gaming indicate fishiness among Sanders supporters, with BerniBrah’s acting in their established somewhat obnoxious pattern? Or does it indicate a good GOP strategy? Or does it indicate that the Sanders campaign is doing something right? I suspect this is a question that will be addressable at a later time, not now.
And, to be clear, the political experts are generally in agreement that the debate was fairly even and Clinton addressed some concerns very well.
So putting this together, a few things things seem to emerge. First, realistically, there are two excellent campaigners running in this primary, each very able to handle themselves. Sanders has not done his homework on the foreign policy issues, as he really should have done by now. (One of his answers was almost GOP-esque, when he was asked about one country but spent a couple of minutes not addressing that country at all, and instead talked about a different country.) Having said that, I suspect that Sanders and Clinton supporters are different. Sanders is an insurgent candidate, and his campaign is following, in part, an unconventional path to the nomination. Last time that happened, the unconventional path worked. Sanders supporters hope this will happen again. But usually it doesn’t.
Someone who has been following the race very closely (full disclosure, a Sanders volunteer) recently told me she felt it was “easier to switch from being a Clinton supporter to a Sanders supporter than the other way around.” In a way this may be the definition of a (successful) insurgent campaign. The reason, she said, is because one of the main reasons to pick Clinton over Sanders is electability, and as Sanders demonstrates that this is not a issue, things change. We start out with Sanders the Socialist vs. Hillary the Hated. The Hillary the Hated persona is not going to change because the GOP has ingrained that as part of American political culture. But the Sanders the Socialist trope cold tear off the mask and become Sanders the Insurgent.