This tweet is the clearest way of summarizing:
https://twitter.com/ezraklein/status/1191511219036803072How has this changed my priors? First, Warren's support (and to a lesser degree, Sanders's) are limited beyond the base. These numbers are horrible considering how unpopular Trump is. That isn't insurmountable - Trump's support was also
perceived to be limited in its appeal. If either of these candidates wins the nom they'll have to be
much smarter than they have been about adopting leftist positions. Neither has really shown much restraint here and that's a pretty smart way of interpreting these results.
With that said, there's still plenty of room for things to change. Even as Trump was running away with polling in late 2015 there was still a polling consensus that he'd get slaughtered in the general against Clinton. There are elements of Warren and Sanders's campaigns that show some ability to adjust here - Warren's campaign was steadliy gaining traction in a crowded field (until recently) and Sanders has an image as a fighter for the common person. But they need to be very strategic in how they campaign because there's still plenty of room to turn off people who dislike Trump but not enough to vote for, e.g., health care for illegal immigrants.
E: Also worth noting that Dems are underperforming what you'd expect for Trump's polls
because the mean education levels are so much lower than they are in other solid D areas.
