The new WBUR poll is the latest. It finds Sanders is the choice of 29% of likely Democratic primary voters. That's well ahead of Buttigieg, who led in December but is now in 2nd place with 17%. Biden (14%) and Warren (13%): tied in third place.
Steve Koczela, president of the MassINC Polling Group cautions that with 3 weeks to go until the primary, much can change.
The 78-year-old Sanders does particularly well with younger voters. According to the WBUR poll, he has the support of 52% of Democratic voters under 30.
While the WBUR poll is the latest evidence of a Sanders surge, it also shows that overall support for Warren has stalled.
'It's not really that voters have turned on her, it's just that she hasn't attracted more support over the last four to six weeks, or so,' said Koczela.
In the WBUR poll last month, Warren had 12%; according to the new poll, she is up by just 1%.