Can you imagine any would-be Sanders voters voting for anyone other than Hillary Clinton should the Democrats nominate Hillary Clinton? I don't see a Ralph Nader this time.
Jill Stein of the green party is running again. Last time, there was no real left-wing opposition to the democratic candidate, so she didn't get very far. But this time, Sanders is generating lots of anger at establishment dems, and he may not enthusiastically endorse Hillary when he loses. So there could be real room for Jill Stein to sweep in and get a few of those currently supporting Sanders. Even just getting to 2 or 3 percent statewide could hand NH to republicans.