Just days before the election, a new poll by one of America's most trusted pollsters has Democratic presidential candidate Kamala Harris leading her Republican rival Donald Trump by three points in deep-red Iowa.

The new poll, conducted by Selzer & Co. for the Des Moines Register and Mediacom was released on Saturday, prompting polling analyst Nate Silver to write a swift analysis, calling the poll "shocking" and saying releasing it "took guts" to release it.

"[Ann Selzer, president of Selzer & Co.] has a long history of bucking the conventional wisdom and being right," Silver wrote, on his blog Silver Bulletin. "In a world where most pollsters have a lot of egg on their faces, she has near-oracular status."

This poll surveyed 808 likely Iowa voters between October 28 to 31 and had a 3.4-point margin of error. Of the respondents, 47 percent supported Vice President Harris and 44 percent supported former president Trump.

Newsweek has contacted the campaigns of Harris and Trump via email for comment.

For Harris, the poll reflects strong momentum among women and older voters in Iowa. The Des-Moines Register reported Harris had a 20-point lead among women (56 percent to 36 percent) and a striking 63 to 28 lead among women over 65.

Independent voters also seemed to be shifting Harris' way, with independent women favoring Harris by 28 points, even as independent men lean toward Trump by a smaller margin.

Selzer's poll shifted Silver's polling aggregator model to Harris 45.4, and Trump 48.8 (giving Trump a winning margin pf 3.4 points). Before the poll, Silver's model had given Harris a 9 percent chance of winning Iowa, but afterward that nearly doubled to 17 percent.

Polling aggregator FiveThirtyEight gives Trump a 93 percent chance of carrying Iowa, and Harris a 7 percent chance.

Silver ranks Selzer & Co. as one of the top two pollsters in America. FiveThirtyEight ranks the firm 12th on its list 282 pollsters for its track record and methodology.

Betting market website Polymarket shifted its odds in Harris' favor after the poll was released, dropping from a 96 percent chance of a Trump victory on Friday to an 80 percent chance on Sunday.

The findings mark a significant shift from earlier Iowa polls, including Selzer's June survey that had Trump ahead by 18 points against President Joe Biden, who was then the presumed Democratic nominee.

By September, that lead had narrowed to 4 points over Harris, before flipping in her favor this month.

Silver called Selzer a "maverick" for releasing the poll, given that, in his view, many other pollsters are "herding" together by publishing results that are almost an exact tie.

"If you had to play the odds, this time Selzer will probably be wrong," Silver wrote, pointing out that other polls still show a Trump lead, including an Iowa poll conducted by Emerson College, also released on Saturday, where Trump leads by 9 points, carrying 54 percent of the vote against Harris' 45.

The Trump campaign swiftly rejected Selzer's poll findings, calling them an "outlier" in a memo circulated hours after the poll was published.

Campaign chief pollster Tony Fabrizio pointed to the Emerson College poll which he argued "far more closely" reflects Iowa's electorate, especially given party registration trends favoring Republicans since 2020 and the consistency of Emerson's results with previous exit polls.

"Unlike Emerson which transparently reports its share of partisans and the 2020 vote recall, Des Moines Register does NOT disclose the distribution of this information, even though they asked it in their survey," Fabrizio said.

Former pollster Adam Carlson posted Fabrizo's memo on X Saturday, writing "this is definitely something a non-panicking campaign would put out."

Trump carried Iowa by 9.5 points in 2016 and 8.2 points in 2020.