I don't think this is as bad for Warren as a lot of you seem to think, mainly for the reason that it isn't about who watches the debates (I imagine not that many people will and many of the ones who do are political junkies for whom the debates will mean less) as much as what the news media spins afterwards. And Warren seems guaranteed to get attention from her debate.
Yes. I mean, the headlines for Debate 1 will be something like: "Warren says big policy words. [Booker/Castro/Klobuchar] surprises." Whereas the headlines for Debate 2 will be something like "[Sanders/Biden] says something surprisingly negative about [Biden/Sanders]. Harris was also around." Warren will almost certainly get positive coverage, while one or more of Biden and Sanders will start to be branded as "negative" - this isn't a bad look for Liz.
