Friday night's Democratic debate in New Hampshire mostly rehashed the participants' past arguments and rhetorical styles, and it didn't generate a dramatic candidate confrontation or meltdown despite repeated attempts by the moderators to incite conflict or trap a candidate in a "gotcha" moment. Amy Klobuchar seems to have been anointed the winner by prevailing news media sentiment, but this evaluation was based more on the perception of a series of fluid, well-crafted remarks rather than a killer moment destined to be frequently replayed on cable news or spread widely on social media.
Most likely, that means the evening's proceedings won't have much of an influence on the polls. A debate's impact on the horse race tends to be maximized when it generates a single attention-grabbing segment, and only one of the seven previous debates this election appeared to produce a clear subsequent shift in candidate support: the first debate last June, when Kamala Harris attracted widespread publicity for challenging Joe Biden over his school busing positions in the 1970s. It's hard to think of many past examples of a candidate who gained a significant post-debate bounce based on a general media judgment that he or she just "did the best" over the course of the evening.
But if Klobuchar indeed gets a popularity boost in the final days before Tuesday's New Hampshire primary, it's most likely to work to the ultimate strategic advantage of one of her opponents—in particular, Bernie Sanders. As a conventionally partisan center-left woman, Klobuchar's profile overlaps less with Sanders than with any other major candidate in the race. A last-second Klobuchar surge could deal major blows to Pete Buttigieg (by potentially denying him a valuable victory in New Hampshire) and/or Joe Biden (by relegating him to a fourth- or even fifth-place finish in the state), who at this stage must be considered Sanders's two main rivals for the Democratic nomination.
Sanders didn't seem to get much credit from the media for his performance in Iowa; the press had expected him to win, weighed Buttigieg's apparent narrow edge in the state delegate count much more heavily than Sanders's larger margin in the raw vote totals, and was enticed by the novelty of the Mayor Pete phenomenon. But the damage that Iowa inflicted on Biden's campaign arguably left Sanders in the best position of any candidate in the race at the moment. At the very least, Sanders is currently likely to finish either first or second in each of the first three early states, he has what appears to be the best-funded and best-organized national campaign (not counting the untested Bloomberg operation, which is hamstrung by its risky "wait until March" strategy), and he would benefit the most from a prolonged multi-candidate race in which two or more non-insurgent opponents jockeyed with each other for support.
Of course, the outcome is still unclear. Today's polls suggest that Sanders is in danger of losing New Hampshire to Buttigieg, which the press would interpret as a serious setback considering his 22-point victory there in 2016, and Biden could yet rebound if he can manage to survive until the race moves to the friendlier terrain of South Carolina. But without much reason to believe that Klobuchar has more than a minimal chance of launching herself into actual contention for the nomination at this stage, any temporary good fortune for her is probably even better news for Bernie.