Elizabeth Warren has pulled slightly ahead of Joe Biden for the first time in Iowa, as the gulf between the two frontrunners and the rest of the field widens.

Bernie Sanders has fallen to 11 percent in the state, while Warren is running ahead of Biden by a slight margin, 22 percent to 20 percent, according to a Des Moines Register/CNN/Mediacom poll released Saturday evening.

The poll reflects both the resilience of Warren's months-long surge and a potential softening of Biden's campaign. And it exposes the brutal landscape confronting every other Democratic candidate in the state, even as they become increasingly active in Iowa.

South Bend (Ind.) Mayor Pete Buttigieg is now running in fourth place, with 9 percent, and California Sen. Kamala Harris is fifth, with 6 percent.

Earlier this week, Harris’ campaign signaled she planned to nearly double her staff operation in Iowa, while making weekly visits.

Then, hours before the poll’s release, Sen. Cory Booker’s campaign manager, Addisu Demissie, warned in a memo to staff and supporters that “time is running out” for Booker’s campaign and that “we do not see a legitimate long-term path forward” if the campaign can’t raise another $1.7 million by Sept. 30.

The survey is no anomaly, broadly mirroring an Iowa poll released by Focus on Rural America earlier this week. That poll put Biden and Warren in a statistical tie, at 25 percent and 23 percent, respectively.

But while Warren and Biden were significantly ahead of the rest of the field in the latest measure, there are still strong indications the race remains wide open: Nearly two-in-three likely caucus-goers, 63 percent, say they could be persuaded to change their mind after picking a top choice.

Only two-in-10, 20 percent, say their mind is made up about a first-choice candidate. And more Biden supporters (26 percent) than Warren supporters (12 percent) say their minds are made up about whom they would support.

Lesser-polling candidates will take a small degree of comfort in the fact that neither frontrunner is pulling even one-quarter of the electorate’s support. In addition, Biden, a centrist, and Warren, a more progressive Democrat, represent different ideological wings of the party, reducing the likelihood that if one of them collapses, his or her supporters would rush to the other.

The poll on Saturday comes in a state where Warren began investing heavily in organization early in the primary. Biden has worked in recent months to catch up to her there, assembling one of the largest organizations in the state and visiting more frequently.

Jeff Link, a Democratic strategist in Iowa and co-founder of Focus on Rural America, said Saturday that Iowans’ views of the candidates have yet to harden – and the race could still swing.

Recalling that then-Sen. Barack Obama trailed Hillary Clinton in the state in mid-2007, Link said, “Remember where we are in the calendar. We have five months to go.”

But there is an enthusiasm gap in Warren's favor. Nearly one-in-three Warren supporters, 32 percent, say they are "extremely enthusiastic" about caucusing for the Massachusetts senator, compared to 22 percent of Biden's backers.

And Warren is the second choice for twice as many caucus-goers, 20 percent, as Biden, who is the second choice for only 10 percent of caucus-goers.

“Warren’s been working her butt off in this state. ... She has got boots on the ground everywhere," said Tom Courtney, a former Iowa state senator and now co-chairman of the Des Moines County Democrats.

From an operational perspective, "Joe Biden, he just doesn't have it together," said Courtney, who is neutral in the contest.

The poll comes as all the major candidates descended on Iowa for the Polk County Democratic Party’s annual steak fry, which drew the largest crowd in the event’s history.

The sharpest divide among likely caucus-goers is between younger and older voters. Biden is the first choice of more than a third of seniors aged 65 or older, 35 percent. But Warren is the top choice for caucus-goers under 35, with 27 percent to Sanders' 11 percent and Biden's 9 percent.

The Des Moines Register’s poll, conducted by the West Des Moines-based Selzer & Co., is considered the most authoritative measure of caucus-goers among public surveys.

The latest poll was conducted Sept. 14-18, surveying 602 likely caucus-goers. The margin of error is plus or minus 4 percentage points.

In the previous poll, Biden (24 percent) led Sanders (16 percent) and Warren (15 percent), though the new poll is not directly comparable to the previous survey because of methodological differences between the two polls. In June, the poll included voters who said they would participate in “virtual caucuses,” which the Iowa Democratic Party aimed to add to incorporate voters who were unable to attend caucuses on Feb. 3, 2020.

But since then, the Democratic National Committee has rejected Iowa’s plans, concerned about the security of the virtual caucuses, which were set to account for 10 percent of delegates awarded. The new survey included registered voters who said they "definitely" or "probably" would attend the Democratic caucuses, with no option for a "virtual" caucus.

Warren is the field's best-liked candidate, with three-in-four caucus-goers, 75 percent, saying they view her favorably. Buttigieg (69 percent) and Biden (66 percent) are second and third on that measure, respectively.

After the top four candidates, Booker (N.J.) and Amy Klobuchar (Minn.) are tied for fifth, with just 3 percent. Behind them, Rep. Tulsi Gabbard (Hawaii), former Rep. Beto O’Rourke (Texas), businessman Tom Steyer and entrepreneur Andrew Yang are at 2 percent.

Gabbard, who was excluded from the third debate earlier this month, is on the verge of becoming the 12th candidate to qualify for the fourth debate in mid-October. According to POLITICO’s calculations, Gabbard only needs to earn 2 percent in one more qualifying poll before the Oct. 1 deadline to make the stage.