Morning Consult poll released on Tuesday shows Sanders firmly in second place, overtaking progressive rival Elizabeth Warren.
The national poll of more than 17,000 likely voters was conducted between 23 and 29 December. It showed former vice president Joe Biden in first place with 32 percent support, with Sanders in second at 21 percent.
This result reaffirms another Morning Consult poll released Christmas Eve, which showed virtually identical numbers for Sanders and Biden.
The Vermont Senator holds the highest favorability rating among candidates in field at 74 percent. Sanders is also tied with Joe Biden as the most recognized candidate, with only 1 percent of respondents saying they have never heard of them.
The poll will be worrying for the campaign of Elizabeth Warren, who was in second place ahead of Sanders in October, when she peaked at 21 percent support among likely voters.
Since December, support for Warren has dropped to a national average of 15 percent, while Sanders has climbed from a low of 18 percent in October.
Support for the former vice president has remained steady since July, hovering at an average of about 31 percent. Biden peaked in a May poll, where his support registered at 40 percent.
Other candidates are registering in the single digits, with Pete Buttigieg in fourth place with eight percent. Michael Bloomberg and Andrew Yang follow with six and four percent respectively.
Senators Cory Booker and Amy Klobuchar, and businessman Tom Steyer are tied in seventh place with three percent each.
