Democratic presidential candidate Sen. Bernie Sanders (I-VT) jumped five points in a recent Iowa poll, while fellow 2020 contender Pete Buttigieg fell nine points. In a Des Moines Register/CNN/Mediacom, 20 percent of likely Democratic caucus-goers said Sanders was their first choice to take office. Sen. Elizabeth Warren (D-MA) gained one point, with 17 percent preferring her for their top choice, and 16 percent of voters said Buttigieg was their number one pick. Former Vice President Joe Biden was the choice of 15 percent of voters in the Jan. 2-8 poll, which surveyed 701 likely caucus-goers and had a margin of error of 3.7 percentage points. Sen. Amy Klobuchar (D-MN) came in at 6 percent, ex-tech executive Andrew Yang got 5 percent, and billionaire Tom Steyer got 2 percent. Those who didn't make the stage for the last debate—Sen. Cory Booker (D-NJ), Rep. Tulsi Gabbard (D-HI), and former New York Mayor Michael Bloomberg—got 3 percent, 2 percent, and 1 percent, respectively.

The number of Iowa caucus-goers who claim they've made up their minds about their primary pick rose to 40 percent, up 10 percentage points since November. Forty-five percent claim they can be persuaded to support another candidate, while 13 percent say they haven't made their pick yet.