The poll found 25 percent of likely Democratic caucus-goers support Sanders, 18 percent back former Vice President Joe Biden, 13 percent favor Massachusetts Sen. Elizabeth Warren, and 11 percent support former hedge fund manager Tom Steyer. Both former South Bend Mayor Pete Buttigieg and Minnesota Sen. Amy Klobuchar have the support of 10 percent of likely caucus-goers, and 8 percent of respondents said they were undecided.