In today's polls, Sanders' momentum continues in a new state - South Carolina.
If Joe Biden loses in both IA and NH, he has to win NV and take SC in a landslide to remain viable.
But in SC, Biden's lead has collapsed from as high as 31% to just 5% in the new poll.
Biden is still front-runner, but Sanders is only 5 points behind.
"Joe Biden leads the Democratic primary with 25%, followed by Bernie Sanders (20%), Tom Steyer (18%), and Elizabeth Warren (11%)."