The Des Moines Register poll released Sunday shows growing support for Sanders in the early voting state of Iowa.
The survey of likely Democratic caucusgoers showed support for Joe Biden dwindling, though the former vice president remains in first place, as the first choice of 27 percent of respondents. That’s down five points from 32 percent in December.
Support for Bernie Sanders has jumped by six points since December to 25 percent, putting the independent senator within the margin of error of Biden.
No other Democratic candidates attracted double-digit support. Elizabeth Warren came in third place, followed by Kamala Harris in fourth and Beto O’Rourke in fifth position.
Neither Joe Biden nor Beto O’Rourke have stated whether they will be entering the race, though both are expected to before the end of March.
Cory Booker and Amy Klobuchar were the first choice of three percent of respondents, while Representative Tulsi Gabbard and Senator Kirsten Gillibrand failed to attract even one percent of support.
Sanders was narrowly defeated by Hillary Clinton in Iowa in 2016, in what was the closest margin in the history of the contest. The Vermont Senator then went on to win the New Hampshire primary.