The latest poll in Iowa -- the state that kicks off the presidential caucus and primary nominating calendar in just three weeks – shows Sen. Bernie Sanders claiming a narrow lead over his top rivals for the Democratic nomination.

FOX NEWS POLL: BIDEN AND SANDERS VIE FOR LEAD IN NEVADA, BIDEN TOPS TRUMP

Twenty percent of likely caucusgoers preferred the Vermont independent as the Democratic Party’s pick to face off against President Trump in the general election come November 2020, the Des Moines Register/CNN/Mediacom Iowa Poll published Friday showed.

The three other top-tier candidates meanwhile fell closely behind him, clustering in a neck-and-neck competition for second place with Sen. Elizabeth Warren, D-Mass., former South Bend, Ind. Mayor Pete Buttigieg and former Vice President Joe Biden polling at 17, 16 and 15 percent respectively.

“There’s no denying that this is a good poll for Bernie Sanders. He leads, but it’s not an uncontested lead,” pollster J. Ann Selzer, president of Selzer & Co., which conducted the poll, told the Des Moines Register.

This is the first time Sanders was chosen as the top pick for president in an Iowa poll. He and Warren, Buttigieg and Biden have each now placed as the lead in an Iowa poll conducted during a fluctuating and crowded 2020 campaign cycle among Democrats. But Selzer added that poll numbers also suggested that Sanders’ “got a firmer grip on his supporters than the rest of his compatriots.”

Since skyrocketing ahead of his rivals in an earlier Iowa poll in November by the same group, Buttigieg notably fell 9 percentage points, placing him in third among Democratic presidential candidates in the race. The poll published Friday had a margin of error of plus or minus 3.7 percentage points.

Of the 701 likely Democratic caucusgoers questioned between Jan. 2-8, 40 percent said their mind was made up on who they would support on caucus night – a 10 percentage point jump since November. But 45 percent said they could still be persuaded on which candidate to support. And 13 percent said they still had not chosen a favorite Democrat vying for the White House.

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“The caucus process is an invitation to keep an open mind,” Selzer added, pointing out that a similar number of potential caucusgoers said they were undecided at the same point before 2016’s crowded Republican primary.

The Iowa caucus is scheduled for Feb. 3, which will be followed by the New Hampshire primary Feb. 11. Other Democratic candidates -- holding out for a last-minute spike in support – polled accordingly: Sen. Amy Klobuchar, D-Minn., at 6 percent, entrepreneur Andrew Yang at 5 percent and Sen. Cory Booker, D-N.J., at 3 percent.