FILE - Bernie Sanders

Sen. Bernie Sanders, I-Vermont

With a little more than three weeks to go before the Feb. 3 Iowa caucuses, Vermont Sen. Bernie Sanders has taken the lead there, according to a new poll released Friday evening.

The CNN/Des Moines Register poll shows Sanders jumping into the top spot with 20 percent support. He is followed by Massachusetts Sen. Elizabeth Warren at 17 percent, former South Bend, Ind., Mayor Pete Buttigieg at 16 percent and former Vice President Joe Biden at 15 percent.

The last Des Moines Register poll in November showed Buttigieg at 25 percent support, 9 percentage points ahead of Warren.

The new poll shows that just 40 percent of likely caucusgoers said their mind is made up and cannot be persuaded to vote for a different candidate. Another 11 percent said they are still unsure who they will vote for.

The poll of 701 likely Democratic voters was conducted Jan. 2-8 and has a margin of error of plus or minus 3.7 percentage points.

Similar to a New Hampshire poll released Thursday, the four top-tier candidates are within 5 percentage points of each other. The Monmouth University survey showed Buttigieg at 20 percent, followed by Biden at 19 percent and Warren at 18 percent. Sanders had 15 percent support.

CBS News polling released earlier this week paints a different picture, however, showing Buttigieg in fourth place among likely New Hampshire primary voters at just 13 percent. Sanders topped that poll with 27 percent, followed closely by Biden at 25 percent. Warren registered 15 percent.

CBS also said its Iowa polling showed a three-way tie between Biden, Buttigieg and Sanders at 23 percent each, with Warren at 16 percent.

In the new Iowa poll, Sanders also topped the field among supporters who said their minds are made up about their candidate, registering 59 percent. Warren and Biden were at 48 percent and 44 percent, respectively, with Buttigieg trailing at 40 percent.

Buttigieg does, however, still top all Democratic candidates in Iowa when respondents were asked which candidates they were “actively” considering, receiving 60 percent. That includes 16 percent as voters’ first choice, 15 percent as second choice and 29 percent as considering.

Warren is at 59 percent under that measure, with Sanders and Biden both at 55 percent.

The latest Iowa poll also had Minnesota Sen. Amy Klobuchar at 6 percent support and businessman Andrew Yang at 5 percent. New Jersey Sen. Cory Booker and billionaire Tom Steyer registered 3 percent and 2 percent, respectively.

Friday’s poll numbers were the last chance for second-tier candidates to qualify for Tuesday’s debate in Iowa.

Biden, Buttigieg, Warren, Klobuchar and Sanders easily qualified under the DNC’s stricter standards, and Steyer made the cut after a strong showing in Nevada and South Carolina polling released Thursday.