Washington Post, by By Philip Bump
...Something happened to Senator Elizabeth Warren (D Democrat Massachusetts). In early October, she was surging in the polls, rising in RealClearPolitics’ average of polls to match (and even briefly surpass) former vice president Joe Biden. At the time, we noted a recent history of people surging into ties — and then fading away. (Ben Carson in the 2016 Republican contest, for example.) That’s exactly what happened to Warren: a peak and then a fade.
Polling from Quinnipiac University released Tuesday allows us to look a little more closely at how Warren’s fortunes have fared. In that poll, Warren slipped from a clear first at the end of October to a tie for third with Sen. Bernie Sanders (I-Vt.). Biden regained his lead, but South Bend, Ind., Mayor Pete Buttigieg climbed into second. (Sen. Kamala D. Harris of California, who surged after the first Democratic debate, continues to poll in the single digits.)
We learn a bit more when we look at the shifts by demographic. Here is age, ideology, income and race. Take a look.
Two things stand out pretty clearly in many of those charts: Warren’s drop and Buttigieg’s increase. Among “very liberal” respondents, both Biden and Buttigieg appear to have gained at Warren’s expense. Her support among moderates, once respectable, collapsed entirely. It’s worth noting that the shift against Warren came after significant focus on her approach to Medicare-for-all — which Quinnipiac suggests has relatively low support among Democratic moderates.