I went looking for some and didn't find this in particular, but found this from Monmouth 7 days ago. A net rating change chart is at the bottom, with Biden plummeting -32 since last May, down to +33 from +65.
Btw, notice that Monmouth's labels have Sanders voters identified as "liberal" and other Democrats tossed together in "moderate and conservative" description. !!!!! There's also a separate "non-liberals" category, whatever that is beyond inviting people to make double sure they're not mistaken for liberals. "No, I'm not one of those wingnuts who hate family values"?
Sanders and I are not in the same category -- both of us agree bone-deep on that. They don't offer a category for Senator "I am not and have never been a liberal Democrat." He also thinks liberal Democrats should give up our conceit of being very different from Republicans and just most honestly identify as conservative Democrats.
New Hampshire Four-Way Fight in Dem Primary
Among registered New Hampshire Democrats and unaffiliated voters who are likely to participate in the February 2020 Democratic primary, 20% currently support Buttigieg, 19% back Biden, 18% back Sanders, and 15% back Warren. Others registering support include Minnesota Sen. Amy Klobuchar (6%), ...
Compared to Monmouths last New Hampshire poll in September, Buttigiegs support has grown by 10 points (from 10%) and Sanders support has increased by 6 points (from 12%). Warrens support has dropped by 12 points (from 27%) and Bidens has decreased by 6 points (from 25%). The race remains fairly wide-open...
Self-described liberals divide their preference among Sanders (26%), Warren (24%), Buttigieg (16%), and Biden (16%). Self-described moderates and conservatives are split between Buttigieg (25%) and Biden (22%). Sanders gets 10% and Warren gets 7% support among non-liberals, placing them at about the same level as Klobuchar (9%), Gabbard (7%), and Steyer (6%) with this bloc. ...
The Monmouth poll also asked New Hampshire voters who they would back if the nomination race came down to just a few candidates by the time of the states February 11th primary. No single candidate emerges as a presumptive front-runner in a scenario involving just the four candidates who lead in the poll right now. Bidens vote share grows by 5 points to 24%, Buttigieg increases 3 points to 23%, Sanders increases 3 points to 21%, and Warren increases 3 points to 18%. Another 5% half of whom are Gabbard supporters say they will not vote for any of these candidates in a four-way race.
There appears to be no natural heir if the field winnows before New Hampshire. Supporters of lower polling candidates tend to disperse fairly evenly among the top contenders, said Murray.
2020 DEMOCRATIC FIELD
NEW HAMPSHIRE PARTY VOTER OPINION
Net Rating (favorable unfavorable)
Jan 20 Sept 19 May 19
Bernie Sanders +46 +35 +54
Pete Buttigieg +45 +50 +47
Elizabeth Warren+37 +55 +39
Andrew Yang +35 +5 3
Joe Biden +33 +42 +65
Amy Klobuchar +31 +22 +33
Cory Booker +24 +31 +42
Tom Steyer +15 +10 n/a
Deval Patrick 5 n/a n/a
https://www.monmouth.edu/polling-institute/reports/monmouthpoll_nh_010920/