LogFAQs > #933503634

Biden leads because he does great with old people, who basically always show up to vote. He's also strong with black people, especially older black people(who happen to be a dominant voting demographic in South Carolina). However, Bernie typically is right on his heels, and does better with younger blacks.

Also, it should be mentioned they last polled in October, which is why Warren has such a huge drop: that was basically her high-water mark. She's been falling in the polls for the last three months, and it doesn't seem like she's done falling: failing to win Iowa or New Hampshire would be fatal for her(and Butt).