Not a standard horse-race poll, but a "who are you excited by" poll.
"For each, please tell me whether you would be excited to see this person run, it would make no difference, or whether you would prefer that person didn’t run."
Excited/No Difference/Shouldn't Run:
Someone entirely new - 66/20/9
Joe Biden - 43/22/31
Elizabeth Warren - 34/23/27
Bernie Sanders - 44/17/38
Deval Patrick - 10/22/15
Hillary Clinton - 23/15/62
I'm not sure why they polled Deval Patrick instead of, you know, literally anyone else.
http://www.usatoday.com/story/news/politics/2016/12/21/democrats-running-for-president-2020/95651728/http://www.suffolk.edu/documents/SUPRC/12_21_2016_complete_marginals.pdf
